Before you ask, just to name a few of the things I’ve tried:
Trimmed any whitespace from fields before output.
Replaced non-breaking with regular spaces.
Collapsed multiple spaces into a single space.
Removed control or invisible characters like zero-width spaces.
Cleared extra spaces between tags using regex.
But the issue remains and the root cause seems to be lying deeper within ACF. I also don’t think all these steps should be necessary in order to output clean text.
