In some profile data I downloaded for informal research, I noticed some cases where games were played long after the last_online date. There were several of these in my sample set of 53, so it doesn't look like an isolated occurrence. Is this a known issue? If so, it seems that my best bet would be to look at the date the last game was played.
Here's an example:
https://www.chess.com/member/RobinsRevenge0
Last game was on November 7, 2023, but their profile data shows they were last online on June 20, 2023: [{'name': 'RobinsRevenge0', 'status': 'closed:fair_play_violations', 'date_created': '2021-01-18 00:05:08 UTC', 'last_online': '2023-06-20 01:05:19 UTC', 'country': 'CA', 'url': 'https://www.chess.com/member/RobinsRevenge0'}]
Used get_player_profile() from the (unofficial) chessdotcom library in Python, if that's relevant.