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It would be nice to understand how you came to the conclusion that this was a Facebook bot.

Ip addresses.

You can check list of IP addresses?

the OP did not (explicitly) check, but you can check if the IP falls into a range allocated to Facebook e.g. https://ipinfo.io/AS32934

Of course I've checked. Here is a recent example. https://news.ycombinator.com/item?id=23491455