Why are so many companies canceling my orders lately?

Sourcing for OA, I’ve had this issue so often recently where multiple companies have been canceling my orders

These weren’t even bulk or suspicious-looking purchases. And some weren’t even during sales, discounts, or using coupons.

I’m trying to understand what could be causing this pattern. I did contact and ask I am waiting for some of them to give me replies

Has anyone run into this before? What are the most common reasons companies start auto-canceling orders like this?

I’m trying to figure out if this is a payment issue, account risk flag, shipping/billing mismatch, or something else on the backend.