like, it removes the need to have an arrow, but what if i want to use an arrow with effects but dont want in in my inventory?

The existence of this mod predates the existence of tipped arrows, so not much thought has gone there. You might be the first to formally request that!

This mod basically just makes the Infinity Bow act like any bow does in creative mode, where if it cannot find any compatible ammo in your inventory, it conjures up a standard arrow to use instead (the arrow that is used is customizable by Neo mod devs, though I forget exactly how and I'm not near my computer at the moment to verify). My knee-jerk reaction is that tipped arrows take a bit more to make than standard arrows, so it still makes sense to require them in your inventory if you want to use them, for balance reasons. I think my goal is to mimic vanilla as much as possible here, with the one slight deviation (and even in that deviation, try to mimic vanilla where I can still).

Though I honestly have not put much thought into it, so I guess I could still be convinced if there's a good argument.

well idrk, it would be cool (but it got nothing to do with the mod) to make the infinity bow able to shoot any arrow u discovered (like which u had in ur inventory atleast once) or the latest 5 diff arrows which got discovered (can be changed by discovering diff arrows), but ig that is not vanilla