Hi @clemclemclem31,
Thanks for reaching out. I understand how confusing it can be when text blocks change size with scaling, and then it's tricky to figure out the real font size afterward. To help us look into this better, could you please confirm the version of InDesign you're using and your operating system details?
It would also be really helpful if you could share a short screen recording showing the exact steps and what happens on your end when you try to check or change the font size. That way, we can better understand the behavior and guide you with the right steps.
Looking forward to your update!
Abhishek