All-time high discount on Citizen Sleeper and In Other Waters:
Citizen Sleeper -75% -> € 4.19
In Other Waters -80% -> € 2.49

KV653RPTUT7KXKA3CMGOG

remove GOG at the end of the code to use it

I think it is "Promotions and hot deals"

Remark: if the FAQ is correct:
How do I get a discount code?
Most of our discount codes and coupons are dedicated only for newsletter subscribers. So if you'd like to receive some interesting offers, make sure you tick the box next to "Promotions and hot deals" in your subscription settings. You can opt-out at any time.

Thanks for the FAQ quote! I thought so too. But I'm subscribed to "Promotions and hot deals" only and not to "Trusted Partners' services" and do not get newsletter discounts anymore (not sure when it started though as I used to get them, maybe when they added that partner option).

Before I bother GOG's support and they tell me that I need to be subscribed to "Trusted Partners' services" ;) ...
Can anyone, who is not subscribed to "Trusted Partners' services" and gets the newsletter discounts, confirm that?

Can confirm. Not subscribed to Trusted Partners Services and receive the discount newsletters. Hope this helps.

EDIT: Sorry for any confusion, I just double checked and I am subscribed to 'Never miss the best deals and important announcements' but am not subscribed to 'Marketing communications through Trusted Partners’ services'.

Citizen Sleeper
In Other Waters
https://www.gog.com/redeem/KV653NM4YTP4JYK7KX

Citizen Sleeper (-75%)
In Other Waters (-80%)

Redeem until January 17th, 2025, 2 PM UTC.

Same as above:

Trus = KV65EC4NE
ted = WMUCU3RXN