I've been having this problem for a while now but just getting around to posting about it. I'm still on the latest version of ios14, I can't remember when this started but I think it was in one of the 14 builds perhaps as far back is when 14 was installed. What is happening when I'm using apple pay it gives me an invalid address error and will not go through, however and this is the odd thing if I back out of the apple payment screen and try again it will allow me to proceed with my payment as normal. I've tried to delete my address under the wallet settings and re enter it and all is ok but when I use apple pay it still tells me invalid address so I have to press the back button and try my payment again and as I noted above it does go through the second time. There are no errors in the address entry and indeed that is my correct address it's showing.
Anyone know what might be going on? This is an IPhone8 running ios 14.8.