Hi, thanks for answering to my post!
We are sadly not using the most recent version of Power BI desktop at our company, our version is a year old (nov 2020), due to too high of a work load for our system admin department.
The issue is persistent in all reports in the Power BI Service, and occurs when NO tooltip is assigned, so it is the default tooltip/hover option that Power BI provides. It only happens when hovering over a slicer, in the dropdown menu when using the slicer to filter data in the report. The slicers we use don’t have the ability to be assigned a tooltip, and those are the visuals where the issue occurs. This may have changed in a later version of desktop, could that be the reason for this problem?
Screenshots below. I'm sorry for the bad quality. I had to block some visuals because of possible priviliged information, and I don't really have the right tool for that.