Yeah, you are right.  I wonder what the most useful (and simple) tooltip would be for this?  Maybe simply "Will reach Level 2 in 7 turns" if you have enough food.  Or "Not enough food to reach the next level" if you don't.

I am sorry to disagree, but the "Next level needs xx" text is very useful because it gives you an idea of how many turns you have to wait until the next level up.

Maybe something like this?

Population 273

Next level at 400 (Capped at 320 due to food reserves)

Needs 127 to reach (47 food left)