Me too! I'm increasingly hearing it on the radio. I first noticed Amol Rajan doing it on the Today programme, then heard it on other stations too.
Ay report instead of uh report.
Thee legislation instead of thuh legislation.
I wondered whether it was to slow speech down and make each word more distinct. Amol in particular had a very fast, run-on delivery, and I do find him easier to listen to now. But the technique does make speech sound a bit artificial.
Edited to say: sorry, just realised this isn't quite what you were talking about, @DuckieDodgyHedgyPiggy ! But in same category of 'weird shit happening to definite and indefinite articles' :😁