I struggled with this on UT. Eventually I installed dufs webdav server and I've been using that with morph.
I can download files from the PC easily and I can push files to the PC easily as well using a web browser. I can even stream videos from the PC this way!

@Vlad-Nirky I don't think it's a regression. I'm not sure how the UT images are baked or how the install process is done by the installer. But it's obvious that I have a Redmi Note 9 kernel instead of a Redmi 9 one.
Maybe there was a mixup and somehow the install script is being instructed to flash a wrong kernel image.
In android lingo, flashing the correct boot.img in fastboot would have fixed the issue.
I guess it's upon the device maintainer to answer these maybes.