mod is for mod loader which is not compatible

What this actually means

A mod declares a Forge/NeoForge version range your server doesn't satisfy.

How to fix it

Either update Forge to the version the mod wants, or get the build of the mod made for your Forge version. Do not mix Forge and NeoForge jars -- they are different loaders despite the shared ancestry.

How to be sure it is this

Read Forge: net.minecraftforge:… in the crash report's System Details, not the jar filename — forge-1.20.1-47.4.10-universal.jar contains two version numbers and the first one is Minecraft's.

What it gets mistaken for

Forge and NeoForge are not interchangeable from 1.20.2 onward, whatever a filename suggests.

What to do next

Match the mod to the loader the log reports. If the mod has no build for your loader, there is no workaround.

What it looks like in your log

Search your crash report or latest.log for any of these:

is for mod loader  ...  version  ...  which is not compatible
requires

The free edition covers the six most common startup failures, and this is not one of them — it is in the paid tool, which checks all 24 and names the mod jar from the stack trace. The fix above is the same one it prints, so you do not need it to solve this.