Issue with AMD + NVIDIA PRIME or Reverse PRIME.

[keen blade]

Laptop: ASUS TUF A17 (2020)

Setup:
EndeavourOS, Linux-zen 6.0.11, KDE Plasma 5.26.4 running on X.

External display #1 connected to HDMI port on laptop, connected to AMD iGPU (4800H Renoir graphics).
External display #2 connected through an HDMI -> USB-C adapter connected to USB-C (DP Alt Mode) port on laptop, connected to NVIDIA dGPU (1660 TI).
Laptop display active.

(I am trying to achieve a triple monitor setup)

Issue:
When I connected external display #2 (as described above, to my dGPU), I started to notice stuttering in games (no matter what monitor they are active on).

Titanfall 2 running through Proton on Steam, for example, locks up KDE Plasma (Application Launcher / KRunner / Task Manager don't work or are frozen, global shortcuts also stop working).

Once I quit the game, it sometimes unfreezes on its own, other times I have to completely restart my system first.

Question:
How can I achieve a triple monitor setup using this laptop without having an unstable/stuttery system (as described above)?

Any help is appreciated :)

[south spruce]

.s litany

[last magnet]

Please follow the Standard Litany when asking a question:
• What was your environment? What was your operating system, configuration?
• What did you do? What did you run or test? Where?
• What actually happened? What were the exact results, complete log contents, exact error messages?
• What did you expect? What were you aiming to achieve? What result were you looking for?

Vague or superficial questions will yield vague or superficial answers. False information leads to false solutions.

Also see this similar guide on how to ask smart questions.

[south spruce]

.s q

[last magnet]

When requesting support, please include specific, detailed, and relevant information about your system and issue.

We need such information because we don't know what it's like inside your system, and it's unlikely that we know much about the issue you're facing. The more information you can provide, the better we can help you with your specific issue.

Some examples of frequently requested information include the steps you took before your issue occurred (such as system updates), the steps you took to resolve your issue and their results, and your environment (such as your display manager or desktop environment).

Vague or superficial questions lead to vague or superficial answers. False information leads to false solutions.

[keen blade]

I provided what my environment was. I provided what I did. I provided what happened and what I expected to happen.