Don’t ask me, I’ve been asking the same question myself 😅

The only things that had originally come to mind were my accounts on those stores being new (but who makes an account there then just lets it sit for like a week), me using virtual cards to avoid using the same payment info across different sites (but many other people do that with no issues), using my non-gmail email (but other people also do that with no issues), ad & JS canvas blocking (but as needanke mentioned earlier, they don’t seem to have problems), or possibly just something with my address itself making its way onto some shared-around list of addresses not to ship to for some reason, but none of these explanations really seem to make sense.

I’m genuinely just as stumped as you are.