Source: http://worldoftanks.ru/ru/news/pc-browser/1/fair_play_9_3/

Hello everyone,

in 9.3, Wargaming is introducing new system to punish suiciders early quitters from battle and AFKers. According to the post, linked above, this is done specifically to punish players, who quit early, depriving the enemy team of one kill for example.

The anti-leaver system

If you try to quit the battle prematurely, you’ll get the following screen

It says “Your team needs you. Quitting the battle until it’s over or until your vehicle is destroyed is considered to be a desertion and can be punished”

After a certain number of these quits (Storm mentioned the number 3), the player will stop getting any XP/credits or medals until he starts playing fair (exact conditions are not known). This system will not be applied to complete newbies.

AFK checks

A new AFK check system is implemented. If the game recognizes you were inactive in battle, you will – just like above – after a warning, stop recieving XP and credits. This system does however take newbies and situations where for example you lose internet in account.

Suicide checks

Practically the same goes for intentional suicides as for the matters described above. First a warning if you suicide and if it repeats itself, 0 creds/XP/medals for you. Random accidental suicides will not be punished.

Basically, if you see the warning window, you aren’t getting anything for the battle. Next battle will be okay, but your account will be flagged If the behavior as described above persists (a flagged account gets punished), you’ll get fined for longer time.