For online we don't see that, and then there's the element of RNG (random) that is on their side. They can shuffle every x deal, or not. So I don't think the card counting will be effective in online games.
If you know how many decks there is in the shoe, you can see if you will be winning. There is no RNG in blackjack because there is a fixed number of cards in the deck maybe the chances are what you are talking about. It is unfair for people to just kick you out or ban you because you are winning.
That is if "you know", Lol, you have really played on an online black jack? regardless if it's live dealer or not? or played in a traditional based casino? You can read ToS of some famous online gambling sites and you will see that they have all the power to even not pay you if they suspect you are cheating them. I put RNG because I'm thinking of a blackjack with no live dealers. But with live dealers still the same, just look at the video being posted.
The same in a traditional based, card counting is not illegal, but if the pit boss recognised you, or they have a slit hint that you are doing it, you get kick out and your pictures and info in the "Black Book".