Are we sure they didn't air the first episode of the previous season instead of a new one then? That started airing in 2017, so the copyright date and endcap would be correct.
ITV Hub says it was Series 30 - Episode 10. Although later episodes of Series 30 have aired, I can't find any record of Ep10 airing previously.
There’s probably a whole bunch of Series 30 that still haven’t aired yet. I wouldn’t be surprised if ITV have quite a backlog of YBF episodes, seeing as they hardly air it these days and yet it still seems to be in production. So I expect they’ll use these Tuesday/Thursday slots to work through their stock.
Looks like Thursday’s episode is actually from Series 29 according to Radio Times, yet once again the show’s Twitter account is billing it as a new episode, so it probably hasn’t aired yet.