For me, this was caused by the Nvidia Omniverse plugin. The workaround in [UBT Bug] No longer able to compile plugins in standalone since 5.3 - #11 by Sam_Swain worked for me.
It looks like what happens is that there is an extension method that takes no parameters that only exists on the type that is expected to be returned from enumerating each plugin. If the plugin has a bug and doesn’t return the right type, the method is missing, so the base method that requires the element parameter gets invoked, resulting in the exception about the required parameter being null. Using the workaround, you can identify the problematic plugin(s) and/or suppress the error.