Cannot remove formatting of pasted text

This is a special font: STIX Two Math. I get the same issue you have. Even in TextEdit, the destination font is not used when pasting (BTW, I use shift + command + V to paste and match style.)

I don't know if it's an issue with macOS. I'll let you do some research. In the meantime, a clumsy workaround would be to paste in TextEdit, change the font to a more usual font, copy the text and "paste and match" in your destination document.

6x6 wrote:

I don't know if it's an issue with macOS.

It's not. The text has been done in a different Unicode range, a not uncommon trick when people want to post bold or italic text in an app which does not yet have the usual options found in a word processor (Apple Messages is an example). No font change is going to affect it. Easiest is probably to take a picture and then use Apple's built-in OCR to convert to the normal ascii text.

One thread should be enough.

Continue here: discussions.apple.com/thread/255678300

Thanks Tom. After reading the link posted by @Urquhart1244, a thread in which you participated, I understand the issue now: My clumsy workaround would never work.