As a side note, although this is not in the group rules, I have often mentioned that the occasional question about Groups.io itself, and how to use the service or problems with it, are OK. If you can't get a mailing list service to work (regardless of which one) there's no point in having it.
The above having been said, if you have suddenly stopped receiving Groups.io messages, whether individual messages, digests, etc., that you have been receiving for years and have not received any notices from Groups.io either immediately prior to or after this happening, I'd be getting in touch with your email service provider to see if they can figure out if there is an issue on their end.
If you check with friends/acquaintances that you know from Groups.io groups, and confirm that they're still getting messages, then you can be quite certain that Groups.io itself has not suffered an outage. And if there's no Groups.io outage, and your message spigot seems to have been turned off, it's not likely to have occurred other than on the receiving end, that of your email service provider, rather than the sending end.
Brian - Windows 10, 64-Bit, Version 21H2, Build 19044
You can't crush ideas by suppressing them. You can only crush them by ignoring them.