ну дела... я думал что это мне кажется, ан нет, оказывается и правда если мешить много кнопок одновременно, сразу вылетает из игры.
Online match crashing - The Game Session has Desynchronized
This crash is caused by pressing down two or more buttons while in the middle of a combo during online play.
For example, using scorpion, if you are performing the 3 kick combo (fk fk bk), pressing fk-fk- then any two buttons at once will cause the match to crash and the "desynchronize" message to pop up.
This crash also occurs using a wide variety of other characters (which I haven't been able to pin down due to PSN outage).