I noticed if I have two containers open (say a pouch and the Traveler's Chest) and I sort by weight in one then the other also gets sorted by weight. I can see some utility in that but I can also imagine it frustrating others.

then they are the same bag which is lazy coding not a bug

I thought that might be what it was (one container). I'm not sure it's necessarily lazy coding - like maybe it's more efficient just reserving a big bucket for inventory and the different containers are just different views into parts of that bucket. I have noticed that sometimes when I open up a pouch or a backpack after having dropped a bunch of items in that there are a few rows of empty spaces (which could be a different thing but I figured they could just be padding it for some reason). I've never written anything like BG3 with tons of inventory so I don't feel I'm in a position to criticize. I think it's all really interesting though.

define the difference between "efficient" & "lazy" coding?

yes everything you posted is coorect but also yes this error is not just a once off

Larian [as a company policy] arbitrary adds / removes/ changes code in their games all the time but never includes solid documentation... in my experince this is why every hotfix and patch for all their games is as likely to create new bugs as it is to "fix" older ones

as a coder is really hard to fix something in act 1 when that may also be the code that breaks another thing in act 3 or needs yet more code that was dropped from the game to meat a deadline

Yeah I can't imagine the headache (especially with a game this big). I don't begrudge them at all.

As for efficient vs. lazy coding, I meant that it seems to me it'd be more efficient to just allocate a huge chunk of memory for inventory then sort of map different areas of that memory to different containers (instead of destroying/reallocating memory for new pouches/backpacks/burlap sacks/etc). It's just speculation though - I've never created an inventory system for a game. Maybe it doesn't matter.