The only people who get hps every turn during the fight are those who get hit.
So? That's still reducing the amount of damage that they take by a lot, especially because it regenerates every round, without any actions required by you to take on subsequent turns to maintain, or even concentration.
The others just get an extra 1 or 2 if they roll higher the following turn.
Which is still good.
As for "lasting" hps, a casting of aid at 3rd level is about as many "lasting" hps, but they are actual hps, generally
last longer and stack.
But this doesn't take spell slots, regains on a short rest, has a ton more benefits
and it stacks with Aid and similar buffs.
I have played with a twilight cleric and I did not find it as overpowered as people claim. Powerful yes, extraordinary no and there are more effective ways to buff yourself. The biggest benefit of the channel diviinity is it is not concentration so you can combine it with something comparable.
From my experiences debating with you on similar topics of balance before, we have very different definitions of what "balanced" is. I've had a twilight cleric in my campaign, and I found that it was more powerful than any ever cleric that's ever been at our table, and was the most powerful character at the table by far (the other characters were an Oath of the Ancients Paladin and a Tasha's Beastmaster Ranger with a Beast of the Land). Neither of the two other characters were underpowered, they were both really powerful, but the Twilight Cleric blew them both out the water in terms of sustainable damage, buffing, and utility.
I don't think it is as strong or disruptive a subclass as a Fey Wanderer or an optimized Bladesinger. An llth level fey wanderer every single turn can take an action, have his Fey (and he can have up to four of them) each make another attacks and each Fey cast a charm and can do that every turn, going Nova that is 6 attacks and 4 charms every single turn, while running a concentration spell on top of that to boot. They can do all of that every single turn, and the charms last for the battle or until they get damaged with no follow on save every turn. If they get lucky and save against the initial Charm the Ranger can redirect one a turn using beguiling twist. Against a single boss man you can attack him 3 times then charm him mutliple times so he can't attack you until he is damaged and do it again next turn (damaging him first to break the charm, then charming him again).
Hang on a minute, because there's quite a few flaws with your argument here.
First off,
that's at 11th level. Most campaigns barely reach that level and end soon after they get that high. Twilight Cleric gets Twilight Sanctuary
at level 2. You're comparing apples and oranges here.
Secondly, Fey Reinforcements takes a 3rd-level spell slot to use more than once each long rest, which you only have 3 of at that level, which means you can, at maximum if you only use your 3rd-level spell slots for this purpose, cast non-concentration Summon Fey 4 times a day. Twilight Cleric gets Twilight Sanctuary at level 2 and gets 2 uses per short rest of it at level 6,
and it doesn't take spell slots.
Third, fey summoned by Summon Fey can be killed much more easily than a Twilight Cleric can be.
Fourth, it takes 4 rounds to spam Summon Fey to get all uses of it out at once (and this is taking all of your 3rd-level spell slots for the day), when Twilight Sanctuary only takes one action to activate. A typical combat only lasts 3-5 rounds, so while the Fey Wanderer is spending their time Pokemon-ing as much as possible, the Twilight Cleric will be casting Spiritual Weapon, Spirit Guardians, healing spells, and so on. A Twilight Cleric can get much more accomplished in the four rounds that it takes the Fey Wanderer to reach their full potential than the Fey Wanderer will.
Fifth, you're completely ignoring that the Twilight Cleric has more features than just Twilight Sanctuary. They'll also be using Divine Strike, their flight, their advantage on initiative feature, their domain spells, and possibly even their Divine Intervention, while the Feywander that chooses to just spam Summon Fey will be doing that and only that during combat. Even if the Fey Wanderer at level 11 can kind-of keep up buff-wise with the Twilight Cleric through the Fey Reinforcement feature, the Twilight Cleric will be overall more effective in the game because they won't be solely focusing on combat.