So in the previous patch when I got home I opened the League Client and waited for it to patch.
It gets to 100%. I click play. Avira pop-ups notifying me that there's a virus in my computer.
At first, I didn't even care because it deletes all the viruses by itself automatically.
I create a lobby, get into champ select. The timer goes to 0. I don't get to the loading screen. Avira pop-ups again and read the message:
This file: "C:/riotGames-(something)" is trying to harm your computer. This item has been added to the quarantine section.
I was kinda shocked because I couldn't believe it at first. I thought that it might be an error or something. I went to the Avira app and removed it from quarantine. The game loaded normally. From then, I had to remove it every time before every single game I played. Even practice tool. For the past week, it has been okay with League. That file corrupted some other system files though and now I can't open anything that is related to my computer (photos, control panel etc.). I am thinking about contacting Riot Support for that but I don't know if it'll help in any way.
And also, I am pretty sure that it was a trojan virus because of the weird section it had in its file name.