1. Go to PS/Preferences/Plug-ins and uncheck "Allow Extensions to connect ..."

Steps 2 & 3 are not "MUST" but that is my advice for Photoshop.

2. Block all exe files from C:\Program Files\Adobe\Adobe Photoshop 2021 with Firewall Application Blocker (File/Add folder content)
http://www.sordum.org/8125/firewall-app-blocker-fab-v1-7/
(check is your Windows Firewall really turned on)

3. Use Host File Editor to block all Adobe's servers in your "hosts" file (Tools/Block Adobe/Save)
http://hostsfileseditorplus.weebly.com/	

4. Run CSXS.reg and add to Registry

If you get Trial window (at some point, someday, somehow) then replace "Coolorus 2" file in:
C:\Users\username\AppData\Roaming

with file from this archive.