Why does Portainer keep prompting me to upgrade?

This is a broadcast message, and is designed to be read and dismissed. While most commonly used for notifications of new versions, it is also used for other notifications and isn't tied to the version you are running. It is generated at the browser level and stored in the cache. If you use private/incognito mode or clear the cache on restart, the message will keep coming back.

To put an end to it, don't run Portainer in private/incognito mode.