A family of Microsoft word processing software products for creating web, email, and print documents.
I can reproduce this behavior in Word from Microsoft 365, (Version 2602 Build 16.0.19725.20126) 64 Bit (Current Channel). The answers to Nam-D's questions are "Yes" for all three. This is clearly a bug.
Additionally, it isn't caused by an add-in. First because Safe Mode prevents the loading of any add-ins, and second because the only add-ins on my system are ones I wrote myself, so they're unlikely to be on Oliver's systems.
Report the problem to Microsoft's developers by using the Help > Feedback > Report a Problem feature. The developers don't get reports from this forum.