Thank you for reporting the issue. Our investigation revealed that the problem manifests in multiple use cases.
We have fixed the issue in some of the use cases and are currently working on the remaining ones.
Please update your InDesign to the latest version, id 14.0.3 to try out the fix.
We shall update here once we have addressed all the remaining use case
We appreciate your cooperation.
An error occurred while saving the commentMikko commented
It happens to me too on the latest 2021 update (16.3.2) and the one before, running on the M1 Macbook Air. But not just 10-20 times a day, literally every textbox I click on to edit does this as fast as I edit the text. The text will show again if I randomly add a few more characters or resize the text box, it is very annoying.