2024 PSD files not opening with 2020 as of today

Error - Could not open “myfile.psd” because the file is not compatible with this version of Photoshop.

Up until today I've been able to open files going both ways out of Lightroom - but now the party is over I guess.  Maybe a PS2024 update pushed through to cause this?

I need to run 2020 due to a legacy plug-in I use regularly - as well as some actions and other things that haven't been transferred over to 2024.  (Every time a new version comes out all my cusomtizations are left behind - but that's another story)

So what's the solution here - save as TIFF?  (bloat)

I'll frequently start out with something like generative expand or some other modern tool  in 2024 - save and then open in 2020 for all my retouching work... well - not any more - until I get this fixed.

Any other ideas?  Save as - an earlier (or universal) version doesn't seem to exist.

EDIT -

Temporary fix that worked is - save as TIFF to desktop - that TIFF will open in 2020 - then Save as PSD over the 2024 version file location (using 2020) - then trash the TIFF file.  This at least lets me get back to work!