My monitors latency is strange

[BONTO5160]

So I have a Samsung Odyssey G50 165hz 1440p, sometimes the games feel smooth and fast, but sometimes it feels like theres some latency, I checked my render latency its really good, then I tried some settings on the monitor, non of them had an impact on the high latency feeling, then I turned on the G-sync and it made a huge difference I could easily see it, but then when I turned it off, it felt as fast as its turned on, then I remembered that I noticed this before, so why is that, that after a while I have to enable or disable G-sync for my monitor to have low latency, is it a bug or something? The game I tested it was CS2 and I remembered that when I first noticed it was CS:GO aswell but I think its only because its a fast paced game and that the only FPS game I play, in story games the latency doesnt bothered me enough for me to notice I guess