Skill loss itself is fine, the problem is to make it based on RL time. It’s a game, not a job; you shouldn’t need to clock in/out regularly to enjoy it. (Tamagochi had the same issue. Except it was character loss.)

I didn’t play Escape from Tarkov but two good examples come to my mind:

• RimWorld - colonists have ~10 trainable skills. They lose skills over time, faster at higher levels. This encourages specialisation, so when shit hits the fan the game cripples you even harder. (Fuck you, Randy.)
• Nethack - your character gradually forgets spells over time; to avoid it you need to either re-read consumable spellbooks, or use the spell often (thus using precious mana). It’s all about resource management, hoard spells and you’ll get yourself killed in no time, but if you prioritise useful spells you have a better chance of survival.

In both cases the player is always losing something, even with correct gameplay. But neither demands you to treat it as a job.