Unable to go into Game mode from Dekstop mode on PC

Custom Built:

CPU: AMD Ryzen 5 7600X
GPU: AMD Radeon RX 9070 (Gigabyte Gaming OC)
RAM: Kingston FURY 2x16GB DDr5-6000 CL30
PSU: ADATA XPG CORE REACTOR II VE
Mobo: ASUS TUF B870 GAMING PLUS-WIFI

I dual boot with Windows 11

• Steam client version: newest
• SteamOS version: newest
• Opted into Steam client beta?: [Yes/No] no
• Opted into SteamOS beta?: [Yes/No] no
• Have you checked for updates in Settings > System?: [Yes/No] yes

Please describe your issue in as much detail as possible: When I am in Desktop Mode and double click on the icon in the top left to go back to Gaming Mode, everything goes as it should at first. Only when my PC tries to boot into the Game Mode, it gets stuck. The fans sometimes spin up, so the CPU is definitely doing smth.. The startup jingle of BPM/Game Mode also plays at irregular intervals, but it always only plays the first part before cutting off.

I can still boot into Game Mode by js restarting.

Steps for reproducing this issue:

probably can't, but what happened before this issue came up is:

1. I shrank the main partition for SteamOS to allocate more for the Windows 11 one
2. I installed FH6 on Windows (I only have the MS-Store key, i know, stupid decision)
3. I played FH6 until my PC crashed once again (that's the reason I switched to dual boot with SteamOS)
4. I went back into SteamOS
5. Played a game
6. Went into Desktop Mode while still in that game
7. Did some cosmetic configuring and discord chatting
8. Went back to Game Mode
   And now the issue was born

I hope this is enough info since I won't be able to provide more, which require booting into SteamOS, over the next days, since I'll be away from home.

Thx for any help :D

No source files, tests, logs, or reproducible steps are identified. Start by reproducing the Desktop Mode to Game Mode transition on the described dual-boot SteamOS setup, then collect startup and session logs; done means identifying a repeatable cause or documenting the missing conditions needed to investigate further.