I never had it before....but, I have had regular "Twitter Blue" from the very beginning (back before Elon Musk acquired the company). Yesterday I upgraded to the CAD $9.99/month plan (it was CAD $3.49/month previously), but it's got some bugs. I can see a blue checkmark for myself from my iPhone & iPad, but apparently some others don't see it. Also, I can't see it from the web version of Twitter at all.
Apparently, I'm not the only one having this problem:
so hopefully they'll identify the source of the problem soon and fix it. Most others seem to have it working fine, e.g. Jen Sale has a checkmark on the web version: