I would recommend @R0mst3r : try a different thermal paste, use the guide Best Thermal Paste for CPUs 2022: 90 Pastes Tested and Ranked to help.
Before putting on the paste and pads, put the heatsink assembly over the cpu/gpu and make sure the heatsink is flushed and level with the cpu/gpu .
Use thermal paste on the vrams, thermal pads 1.5mm on the power components, and you know the rest. Good luck.
Thanks for the reply.
Since my previous post, I already tried applying thermal pads both on video memory chips and VRM elements, went with 0.5 mm Arctic pads (not the best choice, I know).
Why 0.5 mm? Because I found some info in the comments section under one YT video, where some guy said he contacted ASUS about buying the thermal goo they use in these laptops and ASUS said you can't buy the goo, but recommended using 0.2 mm thermal pads instead.
Couldn't find 0.2 mm pads in my country, so I went with 0.5 mm ones.
And after applying the pads I saw some improvements in terms of temperature. GPU doesn't trottle anymore (no FPS dips after reaching 86° C), but the temperatures are still higher than they were before the whole repasting thing. I got stable 85-86° C in Battlefield V, 82-83° C in Battlefield 3 (11 y.o. game), same 85-86° C in Cyberpunk 2077. And there wasn't any thermal throttling despite reaching the 86° C point, which was the throttling point before I applied the pads.
Curious thing to mention: the GPU clocks as high as 1950 MHz according to GeForce Experience monitoring and GPU-Z logs. I honestly don't remember seeing those clocks before the repasting.
So I tried to lock GPU clock in base values using MSI Afterburner, and even with base clock the GPU temperature was still as high as with 1950 MHz clock.
I don't know if it proves anything, but my guess is that this heat originates from video memory chips.
After that, I disassembled my laptop again to check the contact between the pads and memory chips. The contact is very good, I could even see the text engraved on the surface of the memory chips imprinted in the thermal pads.
Also, I was well aware that you can easily bend the heatsink if it's pulled out incorrectly, so I was careful every time. Judging by the looks of it, it isn't bent, so that theory can easily be withdrawn.
The only thing I could try now is to remove thermal pads and apply thermal paste again, but this time just use more of it.
Because last time I went with thermal paste, not a single video memory chip and not a single VRM element contacted the heatsink well-enough to leave some of the paste on the heatsink (it was squeaky clean in those places when I removed it to apply the thermal pads).
I have hopes this will work as I stumbled upon a forum thread (not on ASUS forums) where the guy got rid of thermal goo and had the same problem with overheating, tried thermal pads and K5Pro (looks like an analogue of ASUS'es thermal goo) with little to no success, but after that some guy in that thread recommended to use a little more thermal paste on video memory chips and VRM, and the OP came back and said it was a success, the temperatures went back to the pre-repasting values.
Will be back with an update when (or if) I do that.