Unfortunately I get the same kind of garbage around closing curly braces / closing parenthesis / dots with this magick filter... It seems to do slightly better with an extra `-resize 400%`, but still very far from as good as what you're getting (to be fair the monochrome filter is not pretty (bleeding) when inspecting the result).
I wonder what's different?
( ImageMagick-7.1.1.47-1.fc42.x86_64 and tesseract-5.5.0-5.fc42.x86_64 here, no config, langpack(s) also from the distro)