Hi janina128,
Thanks for posting. It's definitely important to make sure your iPad and Apple Pencil work as expected. We see you have a question about the text appearance, and we'd like to see if we can help.
For clarification, are you referring to the appearance of some of the letters, like the "u" in "glucagon" in your screenshot?
Are you using the "Write with Apple Pencil" section of this link to convert your handwriting to text? Use Apple Pencil with your iPad
Which app are you using? You mentioned it usually happens with PDF files; is it with PDF files in a particular app? You might test out a few different apps, like Notes or Pages, to see if you can replicate the behavior there as well.
Let us know how it goes in other apps, and be sure to include your iPadOS version as well, found under Settings > General > About.
Take care.