I noticed that on some upper case letters the top part is cut off. It only happens for some letters, like E, B and P, and it does not happen in every application. As an example I added a screenshot when using "Easy Effects"
For posterity, here are my font settings and my system specs:
Is there an easy way to find out if an app is using qt or gtk?
Here the buttons in the header gives it away, that's a common gtk thing. Kde apps have file,... menu at the top usually, on gtk apps that's usually behind an ellipsis button. Default theme is quite different, e.g. gtk is more rounded, buttons have bigger padding. Custom themes can override that, but on store pages you should see the default on screenshots.