My Android no longer receives text messages from an iphone since signing in to imessages on my mac I have a Mac, running Big Sur. I signed in to iMessages, and sent a message to my wife's iPhone.
Now, messages from her iPhone no longer go to my Android, and I can find no way to stop it from sending to iMessage.
Is this a bug? How do I fix it?
Generally only an iPhone will register your cellular number with Messages, but you can check and deregister it here:

https://selfsolve.apple.com/deregister-imessage/

Once that’s clear, you have to be sure her app is sending to the phone number and not the email.