Hello there, @Simonizer80!
Yes, that is entirely normal. We enable "Seasonal Effects" (snowflakes) during the winter season, and you can easily disable them from the in-game settings. To do so, please follow these instructions:
Launch multiplayer and press TAB;
Right-click on your mouse & click on the bottom left cogwheel (= settings icon);
Navigate to "Game" and untick the "Enable seasonal effects" box;
Click "Apply Changes" and close the window;
Now the seasonal effects should be disabled.
Please, let us know if you have any further questions. Your confirmation on the status of your issue helps us to keep the forum organized!