Financial institution login auth codes no longer coming through to my devices since OS updates.

My Mac recently was updated to Golden Gate 27.0 and my iPhone16's latest version is 26.6.2. At some point in the last month the following behavior started: whenever I log in to a financial instutition that uses authentication codes, the codes are not sent to me. They're attempting to send them, but something is wrong. On Bank of America I can see that they attempted to send it, but it didn't go through. They try 3 times each time. All fail. They do not go through to my iphone and they do not go through to Messages on my Mac. A few days ago I saw a thread on here (can't find it anymore) that I think said to reinstall those apps on my phone. I didn't have time to read it thoroughly and now can't find it. The problem is that I am not even USING those apps to connect. I am going DIRECTLY to their websites to login. On one of the apps I was able to login from the iPhone and received a code, but not for one of the others. I believe the instructions in that prior thread were to uninstall and reinstall those apps. Before I do that however, can someone answer how that makes sense since I'm not even USING those apps to connect??