It’s called no enchantment cap,link: https://www.curseforge.com/minecraft/mc-mods/no-enchant-cap

no

No, it modifies gameplay features that could potentially give you an unfair advantage over others. The goal of allowing speedrunning mods is usually to improve performance while still keeping the overall experience as vanilla as possible (or just add convenience, like the timer mode to make timing easier). That's far from being the goal of the mod you are proposing.

no

i think any mods are not allowed.

no, the mod is unfair and may help you get a better time unfairly.