There are numerous issues with how the TV writers do things and this has been the case since Season 1. But, yeah, it's turned real poor since the books were left behind - parts of Season 5, and all of S6 and 7. My gripes with the show as a whole are:
1. Swearing, Nudity, Sex, Gore for no other reason than shock value. When these things are used in a realistic way and for emphasis or to compliment the story, that's fine. But too often this isn't the case. I've lived on 2 council estates with the thuggiest losers for neighbours you can imagine, and even they don't swear like the characters on GOT do. The biggest culprit is Bronn. I mean, imagine you were with someone who continually spoke like this:
https://www.youtube.com/watch?v=Z-6bx8pAmGgIt's just used obnoxiously. People don't talk like this. Even the lowest retard you can imagine has restraint with language. They won't ALWAYS use "fuck" instead of "shag" or "sex" or "at it". There are numerous variations, but Bronn is a one man factory of "cunt" "twat" "fuck"... It's like a bad fan translation... when a giddy teen has the power to make his favourite character swear. Ooooooo how clever! And that's exactly what the TV writers do with GOT... not just with swearing, but with sex and violence and nudity. It isn't clever. But you can see from the youtube video above how it appeals to mindless dumbasses. To anyone with any brain, it just ruins the character and breaks suspension of disbelief. I've been known to swear a lot... so when I complain about characters doing it, it HAS to be bad.
2. The TV writers often substitute reason and realism for mindless shock value. The best example I can think of is when the Mountain crushes Oberyn's head. This was so fantastically stupid. It was so overdone that it broke the realism entirely.
3. Other issues are the changes they've made for no good reason whatsoever - and which work against the fiction. Some things that spring to mind:
Brienne is everywhere (Probably because they caved to whining feminazis). She is kicking ass everywhere. Taking on Jamie Lannister, like it's nothing. Beating the Hound. Killing Stanis. She is literally everywhere being a badass because "we need strong woman."
Stanis wife keeping her stillborn babies in jars. WTF? How absolutely stupid. I read that this awful addition was added because one of the TV writers liked the idea. He then asked his wife if it sounded far fetched. Reality check: If you are asking your wife if a major plot change from the books is absurd, then it's absurd. Stop changing things thinking you know better than the frickin' author. It makes Stanis' wife come across as totally tapped in the head... and Stanis too.
Population numbers / army numbers exaggerated from the book numbers. Why? Because 1 million sounds badass compared to 10,000 or 100,000. It's like the TV writers just forgot or didn't care that this isn't 21st century Earth! I can't remember what the total numbers are for the Wildling army... but I'm sure the TV writers went with an absurd number that never materializes on screen when the war is over. Where are all these Wildlings housed or fed? All this lack of believability because they wanted the number to be larger for "drama".
Littlefinger: Littlefinger in the books is a smart person. He comes across as likable when in fact he is utterly ruthless. In the TV show, he has a sinister look and a sinister voice. He's OBVIOUSLY bad. There is no subtlety. The writers want the audience to know he's BAD by making him into Jafar from Aladdin. I half expect his eyes to start twirling in their sockets.
The King of Dorne being murdered in the way he was... just to wrap up an arc they couldn't figure out. Pathetic.
Generally, every single time those TV writers have changed something from Martin's novel, it has led to huge inconsistencies or problems. Oh, yeah, I forgot... Sansa being sent to the Boltons (what nonsense). No doubt this was done simply so we could see Sansa degraded and raped for yet more shock value. Yeah, she's 18 now... So let's bend her over. If I ever get time, I am going to do my own edit of this show and fix the over use of all that shock nonsense. I'd love to recommend it to numerous people, but they'll tune out as soon as they see the brothel in season 1. They aren't prudes, they just aren't going to tolerate over use of what amounts to porn. If I want porn, I'll go watch it on a porn channel. That brings up a very important point... TV can never be as shocking as the internet. If you want to see shocking things, there are real beheadings, hardcore porn, terror attack victims (you'll see this all the time on Twitter) you name it. It's all there. So adding it in to GOT for "shock" is redundant to begin with and ruins the show.
GOT TV show is still a solid 9/10, but it has some glaring faults - nearly all of which are caused by the TV writers being WAY out of their depth and treating the show like their own personal playground, rather than respecting the author, the books, and intelligent viewers.