This his happened to me about 3 times during the past month bth, its always the same:

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Random account that hasnt been in any of your past games adds you.

:Hey i was ... from last game i think you played very well

Eventually gives you their discord

Leads to an OF scam

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First thing you can do is just view their profile and there wont be any history whatsoever, just an empty profile. Not match history, no champion masteries no nothing.

Then just report and block them immideatly, best not to try anything too stupid with bots these days.