Most likely bio and photo captions. But again, I know up to 10 people with almost identical bios, and that only implies there are probably millions running the same bios. You haven't stated, but it's also very likely that, if you have a bunch of accounts/bots running from the same IP, IG may be comparing all your accounts' number of posts, bios, emails, and/or your accounts' interaction habits. I don't know for sure. This is all very new to me. I have yet to hear anyone complaining about an automated IG message like that.