bad packets is a library for packet messaging between different modding platforms. A Fabric client running a mod built on Bad Packets can talk to a server running the Forge version, and the other way round.
It does not magically make every mod cross-compatible: the mod's developer has to use its API. Builds for NeoForge, Forge, Fabric and Quilt, Minecraft 1.19.4 - 26.2. When a mod on your Minecraft server depends on it, the panel installs it in one click.