TL;DR
- Users who have rooted their phone, have their bootloader unlocked or are using some custom ROMs report that their RCS messages are not being sent, even though RCS shows them as connected.
- The Google Messages app does not show any error messages when blocking RCS messages of these users and does not send the messages out as SMS or MMS either.
- Google famously campaigned for Apple to include RCS messaging in iMessage but is now blocking it for certain Android users.
Verge article where the claim is due to ad blocker mitigation and not browser specific.
You said that you heard it was ad blocker related too. So the initial wave of reports about it being Firefox was inaccurate. Every article about it all sourced a singular reddit post. Just some social media “journalism”.
Anecdotally, which I understand is not a great measure, I didn’t experience this when it was first being reported on. But I pay for YouTube premium, so maybe that’s a difference too