What does the "installed" webhook really mean?

We have a paid confluence plugin. We are getting quite a few “installed” events each day, but I noticed some of them are from existing clients.
My question is what it means in reality. I thought it is sent only one time when the plugin is installed on an instance. But I don’t understand why we are getting (not one) events from existing (paid) clients.

That Webhooks is kinda badly named. It should be called “is-installed-on-this-tenant”. You’ll get it whenever the descriptor is updated (and then the installation is updated) or whenever the instance is restarted (happens less often today because of the Cloud work).

You’ll want to follow the proper guidance by Atlassian and check the jwt sent is proper(it gets sent when there is a reinstallation) etc before processing it (ACE and Atlassian Spring Boot does this for you).