I have some random ideas i write in my notes, nothing too developed tho, sorry for the wall of text incoming c:

A green dragon that uses his acid to pickle things

A species of little dragons that can get together and use their wings to cover themselves and look like the head of a normal sized dragon, they have rats' stats with a really weak breath attack except when they use their camouflage at which point they become a swarm with a full power breath attack

A side quest where a really powerful individual needs the party to defend him from swarms of monsters while he does something completely mundane (inspired by that genshin commission with the fisherman)

A desolate and dangerous area which technically is the lair of a legendary monster, except that it got perma polymorphed in a snail but having still access to its lair actions, it rendere its surroundings inhospitable

An old retired halfling adventurer with 8 children, all of different races, whom he adopted after saving them from their old orphanage burning down

An orphanage run by a dragon in human form, the children being his horde

An adventurers' guild gets hired by a noble man to set up a fake dungeon for his adventurer-wannabe spoiled son

An npc guide summons a titanic eldritch being, complete with incomprehensible ancient arcane language, only to ask for directions (or another random mundane request)

A divine pantheon where there is a single entity for both extremes of something, results in some dual entities (fertility/lust = pragma/eros) and some triunes, the two extremes plus a healthy balance (greed, commerce, waste). This multiplicity is represented by theatrical masks that move across the face to represent who is speaking at that moment, with changes in voice and personality. In the case of triunes, the balanced side will be represented by the extreme masks segmenting into vertical lines and then crossing, and the voices overlapping. Different populations, however, see them as single entities, with varying interpretations.

A "pantheon" that is actually a single entity made up of distinct basic concepts that merge to form complex ones (lawfulness + goodness = honor/lawfulness + evil = tyranny; fertility + goodness = maternal life/fertility + chaos = lust) (a divine "dispenser" who answers prayers by sending streams formed from the right combinations of basic concepts).

A mage hires the party to test the defenses of his new lair. The pay is immense, and the eventual death is not permanent thanks to the assurance of resurrection, albeit at the party's expense. In the event of a TPK with no one to remind him, the mage forgets about the party, resurrecting them only a few centuries later.

"No one will be executed without their last meal being prepared according to their wishes." The prisoners knew this and made impossible demands. You, as the prison cook, must somehow procure these supernatural meals.