You do not need a Mojang server. You need EaglercraftServer.
Before diving into the specific version, let’s clarify the base technology. Eaglercraft is not a remaster, a texture pack, or a screen share. It is a true port of Minecraft Java Edition’s game logic to JavaScript and WebGL. eaglercraft 1.20 client
The original developer (lax1dude) reverse-engineered Minecraft Java Edition and compiled it using TeaVM (a tool that translates Java bytecode into JavaScript). The result is a game that behaves almost identically to the real Minecraft client but runs purely on a webpage. You do not need a Mojang server