An update does not install new kernels - only update existing ones - so the update didn’t install 6.1 - you did.
And for the record - I have been using 6.1 all throgh the development stages - and no issues at all.
I don’t know if it is applicable for your system but take a look at AMDGPU - ArchWiki
It is well-known that the latest is not always the greatest - epecially when running on 10y old hardware.
The linux 5.15 kernel will be supported for years to come some time on Manjaro - one of the perks coming with using Manjaro - but even Manjaro has to eventually phase out the oldest kernels which last happened a few years back when kernels below 4.19 was discontinued.
https://kernel.org/category/releases.html
@Yochanan kindly reminded me that 5.15 LTS has been projected EOL in Oct, 2023 - don’t scream - as far as I know those dates are not set in stone. Check above link from time to time.