Yes, I know Ultimate SEO is an older contrib. BUT it's been working well for me. Until I decided to make it "better".

I moved my store to new hosting, and neglected to check the carry over configuration of the Ultimate SEO module. For some reason, redirects were set to false. I fixed that, and my URLs were now as they used to be. So, while I was in there, I decided to get rid of the instructions of which pages to redirect - and go with the default of all.
Well, this was one of the more stupid decisions I've ever made - it was including my gateway cc processing in that redirect. So no one could enter any "valid" credit card. They would always get "we don't take that kind of card" message.
Coincidentally, they could also NOT enter any kind of comment.
Well, I put back in the specific redirect pages, and everything's working fine. Unfortunately, I likely lost a bunch of orders the last day I can accept them for Xmas delivery.
Sigh.