The problem of ugly PDF icons can be solved using FileTypesMan, this allows us to change the icon of a file extension, download it from this link: https://www.nirsoft.net/utils/filetypesman-x64.zip
Run the program, look for the .pdf extension, right click, “Edit selected file type”, “default icon”, select the icon you want and that’s it.
I designed these especially to follow the brave aesthetic: https://drive.google.com/drive/folders/15dIu6mF68ekWtkXMoCiRyMDfRvhAkI3x?usp=sharing
I hope it works for you