Hi Takuya and thank you for having a look.
In this thread sadly they point to the user that they delete their font caches. Sadly this doesn’t work.
I also tried to delete the caches in ~/snap/inkdrop/common/.cache/fontconfig/
Also I tried to remove the configs from ~/snap/inkdrop/common/.config/fontconfig/ without success
For Chromium at least that I have installed as a snap the dialog boxes look okay there.
But oh I see you also have an .rpm to download. Then I will propably use this one.