This sometimes happens as emails are parsed. More info here: https://www.hitc.com/en-gb/2020/09/03/39-meaning-explained/ There's no real 'fix'

I see the line I pasted into my message is displayed with the apostrophe instead of the actual "'". But the title line with the problem in quotes displays ok.

Also when I put the problem characters in a reply, in quotes, thy are still replaced with an apostrophe. I guess only a screen shot would show it as I see it.

Sounds like the person who sent the email may have created it in MSWord or something originally designed for a webpage using php coding and did not set the conversion correctly for the special character.

So why do you see & # 039 (without spaces) - because the special character could not be converted maybe because the required coding was not done correctly.

re : when I put the problem characters in a reply, in quotes, thy are still replaced with an apostrophe. If you try to type the error you see in a forum question reply form then as it is a html special character, it gets converted correctly.

Try: View > Repair Text encoding