482 is not out of line. Many running the test will have overclocked, skewing the results.
Your 2400 speed ram is likely the cause. Ryzen depends on fast ram for performance. Something like 3600 speed.
I also note that you have mismatched ram, and that can cause issues.
Run memtest86 or memtest86+
They boot from a usb stick and do not use windows.
You can download them here:
MemTest86 is the original self booting memory testing software for x86 and ARM computers. Supporting both BIOS and UEFI, with options to boot from USB.
www.memtest86.com
Memtest86+ is an advanced, free, open-source, stand-alone memory tester for 32- and 64-bit computers (UEFI & BIOS supported)
www.memtest.org
If you can run a full pass with NO errors, your ram should be ok.
Running several more passes will sometimes uncover an issue, but it takes more time.
Probably not worth it unless you really suspect a ram issue.
More relevant...
What might have changed since all was well, or at least better?
I might suspect a driver or windows update.
Do an antivirus check and test for malware infection.