It reminds me of Frank Spencer in Some Mothers Do Ave Em, his character changed totally from the 1975 Christmas Special to the final series in 1978. By the final series he had an air pomposity and arrogance about him, and lost a lot of what made Frank Spencer likeable.
He became very self assured and indeed to the point where his speech style changed. When asked if he was Mr Spencer, he would often reply "I am he" in an arrogant tone. A complete change from the original style of the character.
It’s pretty common in sitcoms (see also film sequels) for characters to become more exaggerated over time. Look at early episodes of Father Ted, Doris in Gavin & Stacey, sometimes it works like in these cases, other times like in The Royle Family it gets a bit silly.
Have to say that's been the best episode of the series so far and even despite covid was brilliant. Great mix of segments, hilarious undercover and the end of the show show wasn't just someone singing as most recent ones have been.