Apostrophes and emoji garbled after WordPress update

Hi, I’ve encountered a strange problem I wonder if someone could help me address. After updating recently to WordPress 5.9.2, my previously published posts are now rendering emoji and quotation marks as garbled text.

For example, apostrophes (‘) are now show up as “a€?” and various emoji are rendered as gibberish, such as “e?‘?”. You can see how an apostrophe now appears in this post:
https://newley.com/2021/12/15/india-investigates-hacking-of-prime-minister-narendra-modis-twitter-account/

And this post contains several emoji that have now been garbled:
https://newley.com/2022/01/27/nn288-see-you-in-the-spring/

I’m running WP’s Twenty Twenty theme, my plugins are up to date, and this is happening regardless of browser.

This has affected a significant number of the thousands of posts I’ve published over the years. I’ve searched online (here and elsewhere) but cannot find a definitive description of what’s up, or how to fix it.

Thanks for any tips,
Newley

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