this is absurd (Bug Report)

Bug report, should be insufficient material

Not really, there is the possibility that through very bad plays by the opponent, you can win, that is why it is not considered insufficient material

But there is no possible way that black could checkmate with a light squared bishop vs an h pawn

As I said before, if your opponent makes bad plays, then there is a chance that you can win and therefore it is not taken as insufficient material.

The only positions where it would be possible for black to win would be light squared bishop vs the a pawn, or dark squared bishop vs the h pawn.

I think lichess should change this, so if a position can't be anything but a draw, then it is a draw

A pawn can always promote to something, thus making it possible.

And please, don't act like you're outraged and have never considered this sort of thing before...it's long been a part of blitz.

If the bishop says to the Black King, 'Master I Am Gone', and martyrs himself, then the h-pawn, happily says, "General Advance!", and promotes himself to the arrogant Queen.

@boogaly white under promotes to a knight and can get mated. It is not a forced win, but helpmate is possible.
https://lichess.org/analysis/fromPosition/8/8/8/8/8/8/5kbN/7K_w_-_-_1_2
(Why do people post without reading chess rules first? I always see threads on 3 fold repetition 'bug' and insufficient material timeout 'bug'. These are not bugs, they are literal features.)

It is only draw if selfmate/helpmate is not possible.