Adobe recently updated Photoshop to run natively on the new M1 Mac processors.
However with this change, Intel based plugins will not appear or run in the new Photoshop.
The workaround is to run Photoshop in Rosetta. To set this goto your Applications folder/Adobe Photoshop 2021: (Select the application and press Command-I, Get Info) You can then enable and set to 'Open Using Rosetta'
NOTE: You cannot do this through Adobe Bridge or another file browsing app. This needs to be done through the Apple Finder.
We are working with Adobe to address and update our plugins.
Apple KB for Rosetta
Adobe KB for known issues with M1 native Photoshop