You might come across repositories like TheCookeringYT/Eaglercraft1.21 . However, upon closer inspection, this repository is described as an "Eaglercraft 1.8.8 javascript runtime" , not 1.21. The project name "Eaglercraft1.21" is often used to attract attention and does not indicate the actual version of the game. A true, fully-featured port of Minecraft 1.21.4 to a browser environment is an incredibly complex undertaking and does not yet exist in the same polished, official capacity as the 1.5.2 or 1.8.8 ports.
Given this, you might be confused as to why you see "1.21.4" associated with Eaglercraft at all. This usually refers to one of two things: eaglercraft 1.21 4 download
are actually "feature ports"—older 1.8.8 versions modified with resource packs and mods to look like the newer Tricky Trials update. Where to Find Authentic Downloads A true, fully-featured port of Minecraft 1