I think this is a symptom of getting old. A lot of jokes work by tricking you to think one thing, and then switching to something else. If you need the misdirection to be explained to you, then the joke falls flat.
David Mitchell compared comedy and cooking. He said that if you go to a restaurant and eat a nice meal one day, you will still be happy to go back and eat the same thing in a week. Music hall comedians used to be able to use the same 20 minutes of material, for decades. If a comedian tells a scripted joke on TV, then its hard for them to use it again, as its just not funny a second time.
That is the appeal of programs like Taskmaster, and I'm Sorry I Haven't a Clue. With ISIHAC episodes from the early 70s, some jokes work fine, but singing the lyrics from one song to the tune of another doesn't work if you don't recognise either the lyrics or the tune. It just becomes a really bad song.
For radio comedy, a lot is available at BBC Sounds
https://www.acast.com and
https://fourble.co.uk/
If there are old sitcoms, that you like, you're probably better to get copies on DVD (
www.musicmagpie.co.uk is good) rather than relying on them still being broadcast or streamed. If you go for the big box sets, then you might also get some DVD extras with commentaries and documentaries. You can then watch the best sitcoms over a period of decades, which will be better than the ones written in the last few months.