Receiving verification codes for closed accounts on Mac Messages, not iPhone

I recently saw some text messages with verification codes for some accounts that I recently closed. The text messages appeared on my mac messages desktop app, but not on my phone. Could this be fake phishing attempts? Why would I see it on my desktop app, but not my phone? It somebody is trying to access accounts that no longer exists? I didn't reply, I just ignored them, but I'm wondering if anything is going on in the background. How should I handle this now?