Problem with simple game key management

Hi all. I have started learning SDL since not much long ago, so i am still unexperienced.

I made a simple pong game (still unfinished) but i confronted a problem i couldn’t find anything about it.
When I use the arrows to move the paddles, they seem to work fine. But if i change from UP to DOWN very quickly, the paddle gets stuck. First i tried enabling / disabling the key repetition but it didnt work. What i would like is to be able to change from going up to down very quickly without problem.

Is this related to the OS (GNU/Linux in this case) configuration or am I doing something wrong?

Thank you.

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