Need map ideas

You seem to have a lot of parkour builds, so I would continue with this theme! Make a parkour puzzle map based on things you like! If what you like is popular, other people might like it too!

A horror map in large suburbs that feels eerie because of its emptiness (with empty parkings, boring houses that feels copy-pasted, things like that, kind of common in american suburbs)

The main scary thing would be its emptiness and lack of people, a liminal-like feeling, and some things that aren't regular, like some things written on the walls like "the end is near" (you can use minecraft heads for the letters)

(There would be no light in houses and everything would feel extremely regular; no paintings, nothing special in houses, always the same pattern of house, no trees in the streets, the grass would be flat, etc)

BUIOLD A MAP who the player search if herobrine is real (no mods, datapacks and commands accepted)

If your atste in mapmaking runs to artistic aetheic, you might try finding a juncture of some of the new biomes (those added since you were last active) and build to socase the new material.
Your 'take' coming on them all at once might be interestingly different from those who saw them added one at a time.

Build a spawn hub

OK. Maybe you can make a town?

Azkaban!

a prision of arkham