If a DS token field is added using the plain_text format with a token inside the text, the token will be double escaped.
Currently Drupal\Core\Utility\Token->replace() escapes all tokens by default @see #2580723: Fix token system confusion, with new function Token::replacePlain() → . So if using plain_text, the result escaped again.
Detect if the format is plain_text, if it is then un-escape the token.
[technically, we escape all the text first, add the escaped token (so both are escaped, then we un-escape both, so they can re-escaped again later]
Closed: won't fix
3.0
Code
The change is currently missing an automated test that fails when run with the original code, and succeeds when the bug has been fixed.
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It's likely this issue predates Contrib.social: some issue and comment data are missing.
I've given this some more thought. I like the patch, but, to be honest, it's easier to create a new text format and use that instead.