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But I'm NOT sandbagging, I naturally lose at rated matches!

I wouldn't worry too much about the warnings it's obvious you're a total beginner and Lichess will see that.But do play casual games until you're ready to challenge people. Learn the basics first. Forking , pinning, en passent,the value of each piece, and so on and go from there. Just study a little about how to learn the game and go from there. xxx
Edit: unless of course you're just having a laugh , in which case don't waste people's time and effort to help you , but ,hope you're not xxx

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