Using waterfall 1.19-496 and a CraftBukkit version git-Spigot-3b314f5-e2790ae (spigot-1.15). When connecting to waterfall with a 1.19 client, a player can not write text on signs. The behavior follows this:
Player places sign
The write sign mode is engaged
The write sign mode instantly disengages, leaving an empty sign
Using waterfall 1.19-496 and a CraftBukkit version git-Spigot-3b314f5-e2790ae (spigot-1.15). When connecting to waterfall with a 1.19 client, a player can not write text on signs. The behavior follows this: