Restrictions on phones after they are deactivated

Hi, I have a couple of questions about where an Xfinity phone can be activated after it is deactivated from Xfinity.

I purchased a Samsung Galaxy A50 from Xfiinity during the summer. Last week I had it unlocked by Xfinity & then I deactivated it from Xfinity. I can use it fine on AT&T now.

The Xfinity IMEI checker now says the phone is no longer compatible with Xfinity. Is that because the A50 is not supported under BYOD, or are deactivated Android phones prevented from coming back to Xfinity?

I also found that Verizon's BYOD IMEI checker says that the phone is not compatible with Verizon.  Are Xfinity phones not whitelisted by Verizon?