Sometimes guitar effects pedal companies launch something limited edition and it sells out and you never see it again, maybe because there were some NOS germanium transistors, some old component they couldn’t get more of.
Other times, they’ll launch a limited run stompbox as a test balloon. Like, would guitar players really put something this weird on their pedalboards? Walrus Audio did just that the Lüm Texture Engine, made 600 units, they all sold out and it was discontinued.