Apple Pencil writes 'black and thick' in the first time you press the pencil when write in mark up
Use the Apple Pencil to write mark up in a PDF file (app file). When new opening the pdf file and writing for the first time, it will appear as a black pen. When you press the pen the second time, will become the last color used or last tool used.
this problem appears when update to iPadOS 17 and recent update to iPadOS 17.5.1 this problem still.