I’ve done some further testing and to cut a long story short this was (at least in my case) user error and you can consider my report closed. I’ll detail it below though in case it help anyone else.
I had overridden email-footer.php to do some custom tweaks and missed the fact that after an update the default email-footer.php template had updated to also include the “<td><!– Deliberately empty….” line. Updating my template to the default and re-adding the customisations solved the issue.
Had I paid attention to WooCommerce->Status->Templates->Overrides I would have seen the warning that: emails/email-footer.php version 3.7.0 is out of date. The core version is 7.4.0
I too have this problem. To re-iterate the problem is that by default the emails are right aligned using the default email-header.php template (see the below image)