How is it possible to lose this game?

ru.lichess.org/ipMTFfoExEz8
I lost this game on time against king and bishop. Can you show what moveorder would lead to me getting mated?

Sure! You promote b-pawn to bishop, then put your king on h1 and the bishop on g1. Your opp puts the king on h3 and gloriously mate you on h1-a8 diagonal. Almost forced :) But yes, I think this is absolutely unfair to give white win here.

p.s. Sorry - you promote "a" pawn to bishop - wrong direction