For me, anything 25 FPS or higher is 100% fine and I’ll be enjoying my time. I never play competitive online shooter games ever, though. All single player ones like GOW and the likes. I game on a 60 Hz 4k monitor. GPU is AMD RX 6600 alongside Ryzen 7 5700G and 32GB RAM. My games are set to meduim most of the time at 4k. Demanding titles are on low. Surprisingly, GOW and GOW Ragnarok are both set to ultra and I still get around 40ish FPS.
Around maybe 40 or so I start to notice it. 50 and higher I’m content. My monitor only supports 60 Hz. Around 20 or less I’m annoyed. It’s tolerable for turn based games though. Not enjoyable, just tolerable.