Spurious Birthday Entry

When entering some dates yesterday I noticed something rather strange and sinister in my Google calendar. For the 22nd of February there was an entry for someone’s birthday. It was not a proper name but an email address which I did not recognise – just a string of letters and numbers, with no ID anywhere. Associated with this was the opportunity to “Wish (nondescript email address) a Happy Birthday”. (It did not appear again on February the 22nd 2026). I certainly hadn’t made this entry and I tried repeatedly to delete it although I’ve discovered this morning that you can delete everything of this kind that has come from your contacts list. Naturally I have done this and it no longer appears on my calendar. It did indeed seem very sinister and I am concerned that it may have in some way compromised my phone. I wonder whether it was some kind of hack – a timebomb waiting to go off! The email address appeared in the contacts lists for of all three of my appliances – PC, laptop and phone. I don’t know where it came from and naturally, I have deleted it from all three lists. Can anyone tell me if I need to take further action on this as I don’t feel at all safe at the moment!