Hextech Rewards

Just a simple question about the Hextech Rewards. I finished a game just now, and a piece of text popped up in the post game chat box saying something along the lines of 'You are ineligible for rewards due to previous negative behaviour on this account'. Is the ineligibility a short term thing (like chat restrictions) or is it a permanent thing? Would be great if a Rioter could confirm, unless someone else has a link to another thread explaining this already. Thanks.
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