multiple modifications on PS from LR

Hello
I'm on MAC.
I wish to make changes with PS 2020 from LR CC.
I save the changes in PS, and I find a new Tiff file in LR.
If I want to return to PS with this new file, I find a crushed file of all the layers created the first time in PS.
How to make the modifications in PS with all the layers created previously?
Adobe tells me that I'm working on a copy...
I can do it on Ipad but not on MAC
Thanks in advance for your help