I also did get this message by opening a project in de Mendix Studio Pro.
Shutdown Studio pro via Task manager, restart the project and there was no warning anymore.
For me, Studio Pro works fine when when declining.
The question is, why this certificate request pops up at all.
For me, this happens with different versions (min. since 9.24.x, but also with 10.6.x) quite sporadically (e.g. every few weeks). But I've also seen it on colleagues PCs.
The certificates seem to be arbitrary, definitively not related to the app.
If anyone has any experience on how they solved the issue or found out why these certificate requests come up every once in a while, sharing this info would be highly appreciated.
What happens if you decline? Why do you need to shut it down by Task Manager?