As part of the new Configuration Manager Operating System Deployment task sequence deployment, announced to email@example.com, on Tuesday (5/27/2022) new upgrade task sequences were deployed to update collections. (https://activedirectory.ncsu.edu/2022/05/new-config-manager-ncsu-level-osd-task-sequences/)
Since the deployments are new, computers are evaluating them which is causing an upgrade notification to show up. This is only an evaluation and the computer will not upgrade if it is already running Windows 10 20H2 and newer. The upgrade notification will go away once the evaluation is done and the computer will not be restarted.