Mana regen ramping over time is bad

The way mana regen works isn't good. The fact that it ramps up over time and resets if you stand up means it fiercely discourages getting up before full mana, so much so that if the casters don't take care to stay seated as long as possible, it has a very real and measurable impact on the group's pace. You destroy your own efficiency if you stand up before full.

If you've been sitting for a while, say from 0% to 50% mana, standing up to loot/reposition/whatever costs you so much. For all intents and purposes, it might as well say "standing up costs you 30% of your mana." That's basically the price of standing up and sitting down again vs. staying seated until full mana.

That's a highly anti-QoL burden to place on players, especially when it isn't actually something the game informs you about at all. It's a really awful piece of game design which strongly encourages maximum possible passivity in groups.

Mana should regenerate at a fixed rate. It doesn't need to be faster overall than it is now, just smoothed out instead of starting terrible and ramping up over time. There are no upsides to the current way. It overwhelmingly punishes doing anything whatsoever besides effectively going AFK after every kill.

At the very least, there needs to be something like a 10-second grace period where standing up doesn't reset your mana regen ramp-up unless you cast a spell or something. The fact that getting up for three seconds to loot at corpse sets you back to zero, and effectively costs you a huge chunk of mana that you would have gained if you had just done nothing instead, is absolutely horrendous game design. This whole "severely punished for not being 100% inactive" is not good and should be changed.

Imagine if DPS worked the same way. After every kill, you get a -50% damage debuff that gradually wears off at a rate of 1% per second but resets if you move before it's fully gone. That's pretty much the same thing, but anyone would call you utterly insane if you put that in a game.