You are hardly the first person in the world who has had their phone number/email/messaging blocked.
When you know it's not you, the reason is always spammers. They spoof other people's phone numbers and email addresses in everything they send. If they beat on one particularly hard, automated systems will flag and block it.
We had this happen with our in-home business. One, our phone number was being relentlessly spammed for a few months. We even had people calling and asking if we had just called them, because that's what the Caller ID said. No, it wasn't us, and we'd need to explain spoofing.
Our email address was hit so hard one time that it was blocked everywhere. We had to go to the Spamhaus web site and go through a few steps to prove the email was ours and get it released.
Short version. Don't blame Apple. Blame the spammers for causing your issues. Related to that, the spammers may not be spoofing anything. Rather, they may have gotten access to your Apple account and are directly spamming from your account. If that's the case, change your password.