You might be better posting your questions in the Catalina forum since they're about Catalina.
. But this is an iPhone issue I think.
I'm not sure, but I think you've done the opposite - I suspect you've forced your iPhone contacts to use SMS instead of iMessage. The colours are actually there to show you the type of communication you have. Green is SMS, blue is iMessage. You can't force a non-Apple device to use iMessage, but you can force an Apple device to use SMS. There is no such thing as an iPhone number or a non-iPhone number. The number is assigned to the phone, and the phone is an iPhone or not an iPhone.
I would find out which iOS version you're running, and then post a question in there.
You could also check one your phone and Mac that iCloud is enabled. On your Mac it's probably form the iMessage program preferences (not sure, I don't use Catalina). On your phone it's inside the iCloud settings, but again will depend on the OS you have.
I'd start with identifying the OSs and devices, and then verify the iCloud settings and iMessage settings.