I noticed that sometimes some other players can see all my cards during the game. (without any special card abilities) How is this possible?

How do you know that they can see all of your cards?

Well I'll try to explain... For example, during the game sometimes you can see, that your cards are highlighted in red... This is especially noticeable, when I've just picked up a legendary or epic card (with special ability). It is hilighted in red for some time, as if another player is reading a description (he's moving from one of my card to another)... and soon after that (if my cards are strong enough) the other player forfeieds or acts as if he knows exactly what my cards are. (I sound like a paranoid, do not I? :D )
That's just one case there are some other reasons as well, which led me to that conclusion. I just wonder if any other players have noticed something like this?

I admit to thinking you were talking about the in-game (TW3) Gwent, but it now sounds like you're talking about the live Gwent, is that right?

Yes that's right...

Ah, then I can't help you, since I've never used it. Sorry.

If you like in-game Gwent, you should try this one, it's awesome.

1) this is wrong forum. Gwent has its own forum

2) I didn't play Gwent for quite a while but as I remember there was a card or cards that allowed player to choose cards from opponent's deck or just look at couple opponents cards.

3) as I remember moving mouse pointer on opponent deck highlighted opponents cards without showing what they are.

So don't worry. Your opponent can't see your cards except when he/she is allowed to by special card/s.

1) I didn't know about the other forum... thx
2) Yes you are right there are several cards with the special abilities that allowed player to choose cards from opponent's deck or just look at couple opponents cards, however in this case (which I've described) opponent does it without using any of those special cards.
3) "moving mouse pointer on opponent deck highlighted opponents cards without showing what they are". That's how it should be, however the problem is that in some cases opponents can see cards which they are not supposed to see...

So it seems that someone cracked this game already and is cheating...
Did you try to raport this on CD Project Red support webside?
Is worth to try.
I need to start play again. Gwent is a great game.