It turns out that the side buttons on the mouse can cause problems with League of Legends.
Players have noticed that since patch 9.19 there are some problems in the game when using the side buttons on the mouse. They warned about this error on Reddit.
Minimizing the game after using the button
One of the Reddit users reported an error after patch 9.19. It turns out that the game may have some problems with mice with additional buttons. After using them during the match, we may be surprised by the sudden minimization of the game.
If your mouse has extra buttons, don’t use MB4.
I do not know if this has already been said, but if the mouse has an additional button, pressing MB4 for the first time during a match can minimize the game.
This is a problem since patch 9.19 and I think it requires more attention. I used MB4 and it caused serious problems.
The players’ reactions show that the problem has occurred in many people, which especially worries those who have some game actions assigned to the mouse side, e.g. some use flash on MB4.