constant BSODs for the past 3 months

Hello! I've been having random BSODs for the past 3 months, ever since I repasted my CPU and transferred it to a different case. I've changed my RAM three times, and my GPU once (from AMD to Nvidia). I've had times where I would not experience a BSOD in a span of a few days after reverting the RAM to default BIOS settings and changing the GPU, but it would happen again while playing a game (Genshin Impact), usually with zoom running in the background. I tried XMP on my old RAM (ADATA D60G), unstable. Tried 3000Mhz at XMP, still happened after a few days. Tried 3000Mhz while tuning RAM, crashed after 4 days. Tried changing RAM (to Crucial Ballistix 3600), crashed after a day at XMP. Tried the new RAM at a lower clockspeed at XMP, still crashed. Even tried loosening timings, still crashed. Driver verifier hasn't found any errors as I type this. GPU has had errors (TDR failure), but driver reinstalls seem to have solved the issue. With my current RAM, at 3200Mhz, 1.4V, PBO on, I managed to be stable for 2 days, but it just recently crashed again (Kernel Security Check Failure, ntoskrnl). This happened while playing Genshin, and having Zoom (waiting for a meeting to start), Telegram, and MS Edge running in the background. I tried opening the latest BSOD minidump in WinDBG X64, and it wouldn't let me analyze it.

TL:DR;

PC keeps crashing when playing games (usually Genshin Impact), usually with Zoom, Telegram, and MS Edge in the background. Have experienced crashing before with just TG and Edge running and my PC on idle.

Can anyone give anymore advice apart from hardware changes? Parts aren't cheap.

things I've tried:

Downclocking RAM (new RAM seems to have not solved it)

changing GPU (more stable now, but crashes still happens)

tuning RAM

enabling PBO (thought it was just unstable bc the CPU wasn't keeping up)

Reinstalling GPU drivers

updating windows, chipset, and other drivers (downloaded thru Driver Easy, but manual install)

reformatting boot drive, but not other drives (will try again with the new GPU if I have time)

disabling PBO

running RAM at default motherboard settings

running driver verifier to check for driver errors (none so far)

Specs:

Ryzen 5 3600

MSI B450i Gaming Plus AC (AB0 Bios Version, not yet willing to risk an update)

MSI Gaming X GTX 1650 Super

Crucial Ballistix Black 2 x 8GB 3600 (running at 3200 XMP, 1.4V)

FSP Dagger Pro SFX 650W

ZZAW B2 ITX Case with 2 exhaust Fans

WD Green 240GB M2 SATA SSD (Boot)

Samsung PM841 Series SSD (Games)

HGST Travelstar 5k1000 1TB HDD (for storage)