Black squares read with Cafeyn

[Raffestin]

Hello. I use the Cafeyn application to read the newspaper and some periodicals. I am very satisfied with it, but black highlights appear randomly on the left or right edges, making it difficult to read. I don't know what to do about it. I tested on an old Redmi Note 8 Pro and no problem. I wonder if this is related to the fact that the XRN14 Pro Pl ...