They've been doing that for a long time. I still have a StatusNet instance under my control, it has the ability to send SMS via email when someone replies or make a post, and you're following them. A couple of years ago, all of those started to fail silently to t-mobile numbers.
Juggled the code a little to make it send to pushover instead, and it's worked like a charm for the last two years.
My mom and I noticed it during the first lock down. She started putting extra letters in links and telling em which to take out or just sending an email.
Yes. They've always been a bit picky about what gets sent, but it's become useless lately.
A lot of that is due to the fact that email and it's cousins have become weaponized with spam. It's easier to just turn it off than to fight the rising tide.
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