I was just about to post about this as well before finding this old thread. I hit the bug with bold text a lot, though not with quoting. When I selected formatted text that includes bold (probably italic too), I get a space between the bold text and the punctuation.
Source Text:
Copied and pasted, Markdown version (Grammarly is underlining the extra spaces):
And rendered version where you can see the spaces being awkward.
I run into this all the time because I often move text like this from WordPress to Discourse. (I’d prefer to move from Google Docs to Discourse, but for some reason, Discourse doesn’t recognize bold and italic when pasted from Google Docs.)