The services that new or don't have much traction aren't blocked yet.
There's sort of a race condition between how quickly new "anonymous" email services appear and how quickly they are banned by other sites.
This isn’t a redirect to your existing email a-la-iCloud+ “Hide My Email”. You close the tab and the address is gone.
Like bugmenot accounts that only last a day or so.
Sorry for the "lmgtfy" type of answer, but I generally do that search then pick a site at random.
I think I tried with it with Twitter, Instagram and Google (when they asked me for a phone number and I didn't want to give my real one); this was about two years ago. Does anyone have better results?
If you just don't want to give out your number you could get a second one? Nowadays with eSim it should be easy to get a "pay as you go" number and only ever receive sms.
As long as you expect to only use the number once then they should be fine.