This is happening for many countries. I am in Australia and get the same thing, no events after December 31 2021.
Let me save you some time wasting. The Apple calendars are missing information, no amount of switching options off then on, or removing or resetting will fix this. To see what I mean have a look at the following url. This is the source of the info for the Apple calendar subscription. You can see it stops at the end of 2021 (as of the time of this posting). This explains why you can’t get info for any 2022 or beyond.
https://calendars.icloud.com/holidays/gb_en.ics
So the only way for the official Apple calendar subscription to start working again is if Apple populate the info in that file on their servers. Until that happens we’re all going to have to suck it up. You wouldn’t expect that update to be much of an effort from them and it doesn’t require any OS updates. Interestingly the US version of that file stops at the end of 2022, so I expect they will fix it then at the latest or their home market will kick up a big stink.
In the meantime, for those using other calendar sources - be careful that your source is trustworthy. Over time there have been security risks with external data feeds containing deliberately crafted malicious payloads exercising security flaws. We have been told the known flaws have all been fixed.. and then we wake up 3 days later to find a new one. The data might be good now, but can you be sure that their server is secure and that it won’t be maliciously altered? That’s a nice juicy honeypot for a hacker, change one file and then have potentially millions of iOS devices updated automagically.
Me? I will keep my subscription to the Apple calendar active, in the unlikely event it will be updated by Apple soon. In the meantime i will use the temp workaround from j0hn4. It works for Australia and other countries and the data source seems clean without annoying ads. Here is a list of all their countries https://www.officeholidays.com/subscribe