I just updated my Photoshop 25.12.0 to the new 26.0 version on macOS 15. In every previous October release for as long as I can remember, like ALL of Creative Cloud, the old Adobe Photoshop 2024 folder would be left in place that contained brushes, actions, scripts, etc. that had been added to the previous version and then i could manually drag those over to the new Photoshop 2025 folder. However this release, the entire folder was removed. It doesn't put it in the trash its completely removed. I have a back up so I can go in and retreive what was wiped out but on my other machine I'm making backups of the plugins and presets before updating.
This happened for Illustrator as well (so will post this there as well). My After Effects however did retain the old folder so I could grab what was in there.
I'm marking this as a bug for now.