I had a look at the trial version of the new release v2. and was surprised and a little annoyed that after saving in 2. I was unable to open the file again in v1. despite not having edited anything and certainly not using any of the new features.
I think is bad, I can open all sorts of PSD files in Photo so I would expect at least some fall back option, not being left with delete or upgrade to the new version.
I was clever enough to test on an old file so nothing important was lost, and I may still upgrade in the future, but not now.
I didn't see a warning about this and it maybe I missed it, if not it needs to be there.
All the best, I love Affinity tools but this is not good.