Warlocks made a deal with the glitch.
Sorcerers got glitched by accident.
Wizards (and EK/AT) found documents in the glitch world and figured out how to cast from them.

Arcane casters, their HP is divided into Hope and Glitch. Wizards & Warlocks start with one Glitch and the rest hope, Sorcerers start with three.
You have some body part glitched in accordance with this, go for the navel or something if you want to hide it.

When you cast a spell against nature or against civilization, you get one hope transmuted to glitch. Max two are transmuted in this way per day, then you can cast freely. For sorcerers, max one. You can use your magic against glitch without problem (but they have ways to transmute you).

When you level up, you get all your new hp in hope.

The transmutation means that you lose one current & max hope and gain one current & max glitch.

When you take hp loss from nature or from civilization, they primarily go for the glitch.
When you take hp loss from glitch, they primarily go for the hope.

When you get more current glitch than current hope, the glitch casts a charm or command or similar spell on you, DC 20.

You need at least one max glitch to use your arcane powers. Greater Restoration and similar spells can un-transmute all-or-nothing on a willing subject only. Those who want to stay glitched, the spell can't un-glitch.

When glitch beings casts damage spells on casters they also heal their glitch. But normal attacks from glitch beings (such as being eaten) don't do this.
So if you have 10 current hope and 0 current glitch (but three max glitch) and they roll an 8, you end up with 2 hope and 3 glitch. Because 8 damage to the hope & 8 healed to the glitch.
When warlocks disobey their patron, they get 1d8 glitch damage in this way.

Warlock players can make the initial pact by give up something big to get a small quest from the glitch, or give up something small to get a big quest from the glitch.

Bards are also divided in this way, but they start with 0 glitch and (unlike wizards/warlocks/sorcerers), they can hurt nature & civilation /indirectly/ (i.e. things that don't cause HP loss) without getting transmuted. Only if their spells cause HP loss to nature or civilization they get transmutated, up to the first three times per day (then they can cast freely. ) They are dabbling with danger.

Works normally and doesn't cause glitch.

Works normally and does not cause glitch. You must have nature as alignment. Your goddess' name is Rarna. Her life-long enemy is Telon. But that was before the glitch showed up.

You're divided but start with 0 glitch. You can cast spells against nature and against glitch normally, but when you cast it against civilization (defined broadly as with wizards, warlocks & sorcerers, not just hp loss as bards) you have a 50% chance of having one point of hope transmuted and becoming more glitchy. Everytime, all day long, no ceiling. You cannot have nature as alignment. Your goddess' name is Telon. She is worshipped openly in the city. Many city guards have her medallions for luck.

Other domains (Light, Life, Death, Tempest, Knowledge and Trickery) are completely glitchified. NPCs only.

Paladins are banned and/or will require lot of work to fit in with this world… or as long as they don't care about good or evil but rather care about the three alignments in this world maybe then they can be pallies.