In Yahtzee, the small straight is NOT 1,2,3,4,5. Directly quoting the instruction book on hasbros website: "Small Straight: Score in this box only if the dice show any sequence of four numbers."
I just checked and you're actually right! What the hell? This is a complete personal Mandela Effect moment for me. I very distinctly remember Small Straight always being five dice. Well, I guess I'm the one with egg on my face on this one.
I just tested and the game does recognize all 4 dice straights as small straight, so yeah, works as intended.