Bought iPhone 17 Pro Max on eBay, was this a scam?

I bought an iPhone 17 Pro Max on eBay recently that was supposedly brand new, unopened, and unlocked.

The seller seems legit with 99.9% positive feedback and a real brick-and-mortar store in New Jersey. Everything seemed fine when I received the phone. The box was sealed with the strips you have to tear off still intact. I’ve seen plenty of sealed Apple boxes and there was no sign of tampering. I set up the phone and transferred my AT&T eSIM with no problem.

But about a week or 2 after I started using the phone, a message popped up asking me to activate a second
T-Mobile eSIM. I declined at first but it kept popping up every few days so I eventually clicked yes. After the eSIM activated, I got a text that just said “Good Afternoon.” I did not respond and immediately deleted the eSIM. Last week I got a call that I did not answer, but they left a message claiming to be T-Mobile support asking if I needed any assistance.

Is this phone hacked? Should I stop using it and switch back to my old phone?

I have already logged into my iCloud on it, loaded my passwords keychain, added all my credit cards to the Wallet, logged in to all my banking apps, set up my email, everything. I have not noticed any suspicious activity on any of my banking accounts, emails, or socials. Everything seems fine.

Is this phone going to scam me somehow?