The problem in my opinion is the matchmaking and the meta.
Due to its nature, the game is not well balanced. Each patch there are certain cards that hold to much power for their price class and are overlooked by the developer, resulting in the feeling that a win is not deserved. Certain factions that get good cards/reworks in a patch are always at an advantage while others
(unintentionally) get left behind. This means the game feels like not a fair competition resulting in less GG s. A good example would be the whole "king of beggars" debacle- from the perpective of a syndicate player its nice ... free mmr am I right

... but it sucks for everyone else.
Furthermore gwent reached a point were certain deck types have direct counters and bad match ups, where you cant do much about it resulting in a lot of frustration for some players. For example if you get matched against a masquarade ball deck and you run only one purify card... its pretty much game over from the start. Its like if usain bolt gets matched against wladimir klitschko in a boxing match.
Besides that some decks seem specifically designed to be anoying or make you feel bad as an opponent , overall fostering a toxic reaction from players - like a mono blue control deck in MTG. This is especially true for some nilfgaard decks which I tend to give less GGs overall together with certain syndicate decks.
Not sending a GG doesnt meen I have hard feelings against someone. I just get salty when things feel unfair. Cheers