Yeah, a Gloom Stalker is notorious for having a near broken ruling on its stealth. Try to see it as someone using stealth in darkness against a creature without Darkvision. You can still hear them and see them move in dim light.That’s the problem. It doesn’t feel dangerous.
Where’s the danger when you are invisible 99% of the time in an underdark campaign? Or
Can bypass most simple traps with a cantrip spell?
When any ill you receive is gone after a nights sleep? That’s not danger that’s a walk in the park.
And about disarming traps, once you know there’s a trap somewhere, isn’t the danger already passed? Maybe I am not seeing how you do it, but doesn’t the Arcane Trickster core feature resolve around being a trap disarmer with a magical hand? That is just the thing they are good at. Do you still make them roll for disarming the trap?
I can’t help but think about how tedious BG3 is with a dozen traps in a row that all have to be spotted and disarmed one by one. If that game had no traps at all, it would have been better in my books. Maybe I don’t like traps.
I am reminded once again about the game Amnesia: The Dark Descent. It is a survival horror game where you sneak around a castle trying to dodge monsters you can’t defeat. The game designers started out by making stealth very skill rewarding: good players got spotted less, if at all. Now from a game perspective, that worked well. However for a horror experience, that didn’t work as well. If people thought about the mechanics of the game too much, it would take them out of being immersed in the story of the situation.
What they did instead is make it very easy to not be caught by monsters. But no matter how well you crouched down in a dark corner behind some barrels, monsters would ALWAYS shamble close to the player location, make some creepy breathing noises, and move on. This got them the experience they were looking for in their game, and it was a great success.
My takeaway from that story is that pursuing a feeling with mechanics can be a challenge if your goal is mechanics and not a feeling. In my last session my players were looting a temple of its golden cupola. This would have been nothing special if there weren’t a CR30 dinosaur sleeping on the temple’s side. The whole session they were all rolling stealth checks, fearing for their lives. Then at the top a stone guardian came alive, and with every blow during that fight, the heroes checked nervously if the scaled and spined giant had awoken. Of course it didn’t. They were level 2 and I didn’t want to kill them. I had prepared for if they did something really stupid, the beast would awaken and spare them if they made an offering to it. So they weren’t in actual danger, but the players felt the danger and really enjoyed it.
Challenging characters in combat can be very difficult if you use the normal encounter building rules. Those rules just suck. CR doesn’t work like it should. If you want to use the most important encounter benchmark, you want to know when a fight can be deadly. Don’t worry about wearing characters down. Players will usually feel like they are done for when they don’t have access to their highest level spell slots. If a pc goes down in a fight, even if they succeeded on every death save or got healed straight away, they still feel like they are in danger.
Let players enjoy what their PC is good at. If that breaks your campaign, talk to them about it and change the feature.