Honestly non at all. I even took a video once with my phone of my steam deck screen next to the pc monitor and the frames were perfectly in sync. The input feels native and i have zero latency with that. I remember years ago it indeed wasn’t that good. But nowadays its so perfect!
I even play competitive counter strike that way.
The stats show around 1ms. And that is network and decoding combined.
As long as you are at home, its indistinguishable from directly plugging in a mouse+keyboard and monitor.
Yeah i like it that i can play the game on the highest quality and it makes the steam deck less hot and the battery last waaaaay longer :)
I also have it connected to my tv a lot so i can play pc games in 4k on the couch.
I also tend to switch between the steam deck and pc multiple times in a day, so having everything on one system is really nice.
Games like vampire survivor, emulators, bind of isaac, olders games etc, i play on the steam deck directly. But having immediate access to my xbox games pass library is also really nice ^^