Says seen in beeper but not in Google

I have a case where it says the person I messaged had "seen" or "played" in the case of a voice note what I sent them in beeper but just says delivered in Google messages, the non-filled in checks. Is this a bug or something? Or maybe some sort of incognito mode in Google's app that beeper doesn't recognize? Im just curious if others have had this and if the receiver is actually looking at my texts or not. Thank you in advance.