Doncaster to Riga is one example - a few flights in December and one or two in January, then nothing til early April.
Several from Liverpool.
Same with Gatwick.
Check their timetables.
These frequencies were reduced two days ago, so was before the latest travel restrictions.
It's pretty obvious what Wizz are doing, opening bases everywhere, launching new routes to great media fanfare (look at the Doncaster press release a few weeks ago) to try and get more bookings to improve their cash flow. Then cancel the flights and issue credits, in the hope customers will book one of the few flights they do operate.
EDIT - it seems as it isn't just the UK where they employ this model, read the comments section on this link
https://www.exyuaviation.com/2021/11...anned-new.html