Why computer doesn't like this move?

lichess.org/analysis/standard/rnbqkb1r/pp2pppp/5n2/2pp4/2PP4/4PN2/PP3PPP/RNBQKB1R_b_KQkq_-
In this position, if Black plays Bf5 - then the computer evaluates the position as +1 for white. But why is Bf5 bad? I want to get that bishop out of the pawn chain before playing e6.

Also, it would be nice if we had a "Simple Questions" thread. :P

Nothing is stable at that time like the center e.g. Other piece placements are more on the agenda. I don’t like Bf5 either, it weakens somewhat the health of the black position imho.