I'll start with: I'm not sure if this can be considered a bug, or if the original behavior was a bug.

My plugin depends heavily on sign block physics events fired when redstone near them changes state. This is so that a redstone signal can trigger a sign, kind of like CraftBook.

Since Minecraft 1.19, at least on the latest Spigot 1.19 snapshot, this event is no longer fired. It does fire for other blocks (like the redstone wire/torch, etc.)