If you can't check for updates to your ArcGIS Pro version because it is blocked.

Stop ArcGIS Pro

Start Registry Editor and change the value of the CheckForUpdatesAtStartup key from 0 to 1.

Click OK and start ArcGIS Pro.

Read more here: https://pro.arcgis.com/en/pro-app/2.9/get-started/update-arcgis-pro.htm