The 2.0 patch and Phantom Liberty is installed and is, on its own, running fine. And I can safely say Phantom Liberty is very much like the base game: it does NOT like to be played in a way it's not meant to be.

TL;DR: it crashes about every 6 minutes. I hope that is just because I forcing plays I am not intended to do.

I've spent about an hour now, trying to break through the Barghest front gate. And the game sure does not intend for that to be done. And very much in Cyberpunk 2077 style, there's glitches and bugs and crashes galore.

First try: I "met" with Songbird (and I already don't like her - next time, just send a card, please), and activated the initial mission. Then I backtracked, and started attacking the Barghest soldiers - and Songbird got furious at me!

She said I had just killed the NUSA president, and that she didn't want anything else to do with me. And I passed out. When I came to, Johnny was next to me, saying "good riddance" and that he wanted a drink. With a notification that the mission had failed.

EDIT
This is how the secret ending is unlocked.
/EDIT

Second try: curiously, after Songbird tells me to get by the guards at the back gate, I am free to attack the soldiers. After multiple deaths and reloads, sprinkled with random crashes (probably trying to reload a save too fast), I am have almost cleared the main gate of enemies. Got a save game this time, which is potentially glitched.

Third try: having killed everyone around the gate, another 16 soldiers and 2 mechs are coming through the main gate (where I am trying to get to). After some more crashes, and a perma stuck "weapon glitch" quickhack on me, I backtracked again...and suddenly the interaction scene with Songbird was forcibly replayed - without Songbird. I could not skip anything, and all VOs was muted. Interaction played as the first time, except I could not skip anything.

After some more crashes, and at least one of the turrets stuck at firing up in the air, I finally got the point of taking out the 16 soldiers...which was much easier to do, I learned, by blowing up their cars as they arrive instead of taking them out one at a time. But just as I killed the last mech...it hit me at the same time, and I died as it blew up. And then the game crashed again.

And that's where I currently am. I guess I have to take on the 16 soldiers and 2 mechs again, as I can't save whenever I want.

The crashes and bugs I can live with - I have played a so heavily modded 1.6 version of Cyberpunk 2077, I am rather used to it crashing by now. And bugs have been present since day 1. But I can't say I like the changes done to the gameplay. Maybe it's too soon to say anything for certain, and I will give a wholehearted try, but there's many aspects I really don't like now.

- First off, there's bullet time events all over the place, with zero warning or deliberate input from me. Which feels more like a loss of control, than an intentional boon or escape mechanic.
- Stats and perks are now spread out everywhere to the point where it feels like specialization is no longer possible.
- Weapon and cyberware upgrades is just a confusing mess, with the cost and stats of anything doesn't feel important at all. I don't want a +3,16 carry capacity on my cyberdeck or whatever.

Bugs and annoyances:
- I had multiple cyberware duplicates when I (finally) got to talk to Viktor - letting him say those 2 optional voice lines now removed the ability to change cyberware. I had to leave his shop to get the option back.
- The Trauma Drama minigame machine is random - for anyone trying to do that hidden mission, just find any slot machine and save and reload. And watch the machine change. And I had to use my Corpo Plaza apartment PC to access the Trauma Team website.
- Why is a NCPD bike easily keeping up with me at 125+ MPH, when I am driving it, it peaks at 84 MPH?
- Cars and pedestrians are now frequently coming out of thin air right in front of me. I guess I have to edit that in the .ini file again, if I still can.

I had many crashes also, reduced Crowd Density to middle bcs they seem to have increased it vs the old game and at medium it still is very crowded at times.

Also disabled Cross Saving - seems to be a scource o trouble for many players crashes.

My CPU was running quite hot and i set SMT back to Auto as it is 2°C cooler.

Also using Fullscreen and not Window or Borderless.

Had not have a crash since many hours after that but i can not say it solved all problems as i am in a different area now doing different quests and tasks.

Disclaimer:
I am not actually complaining here, just wanted to share how the game is set up (outcomes etc.) when doing things differently than the developers intended. The crashes doesn't actually bother me, because I am intentionally trying to break the game. And actually, I prefer the game crashing to the alternative, which is soft-locking. Seen enough of that in other games.

Cross-saving has been disabled since it was released. I only have one device to play the game on, and I knew such a feature would be nothing but trouble.

As for the CPU, I do notice overall usage has gone up - used to be around 80 % utilization, now it's closer to 90 %.
I got an i9 10900K that is overclocked to 5.00 GHz all-core, but I've also undervolted it to 1.235 Volt.
Pushing it to 5.1 GHz all-core required 1.4 Volt to run stable, which was way too much for my Be Quiet Dark Rock 4 air-cooler.
Temperatures currently peak at 86°C for the CPU, and 61°C for the GPU. Got a Be Quiet Silent Base 802, with Corsair ML120/140 fans with a rather aggressive custom profile.

I know Windows resource manager treats full screen applications with higher priority, but I got 5 screens, and if anything run in Fullscreen, every other screen goes black. And I am multitasking way too much for that to be a viable alternative.
Also - and I don't know whether this is still relevant - one of the old tips for making Cyberpunk 2077 crash less, is to run it in Borderless mode.

And doing different quests and tasks IS the way the game it's meant to be played; I am just trying to break it. :)

Okay, I finally got through the Barghest checkpoint...but sadly, and as I was starting to fear, it's just a checkpoint similar to the border crossing checkpoint in the Badlands.

Killing everyone doesn't actually yield anything - it's still not possible to pass through.

EDIT:
But I don't understand what the game means here:
Now, in the "Dog Eat Dog"-mission, the quest says "Talk to Songbird", with a quest marker leading to a point near the Luxury Apartments fast travel point in Westbrook. But if I actually go there - and the quest path is leading to somewhere below the building - Songbird gets mad at me (again claiming I killed Myers), and the mission fails.

In the same quest, I got another quest marker saying "Go to the garage".

EDIT 2:
Okay, so I've passed the old parking garage...and I have to say, this has been my worst nightmare!
Climbing a derelict building, in low-light conditions (seriously, no flashlights in 2077!?), with fatality falls everywhere, with loot, secret and obvious, sprinkled around as carrots? Having obtained everything now, even if I have not, I am NOT going back!