MtoA 4.0.4 Maya 2020.1
00:00:00 WARNING | [mtoa.attr] CExtensionAttrHelper was passed an unknown Maya node type "bifrostGraphShape"
00:00:00 ERROR | [mtoa.attr] Unable to create extension attribute .aiUserOptions
00:00:00 ERROR | [mtoa.attr] Unable to create extension attribute .aiVisibleInDiffuseReflection
00:00:00 ERROR | [mtoa.attr] Unable to create extension attribute .aiVisibleInSpecularReflection
00:00:00 ERROR | [mtoa.attr] Unable to create extension attribute .aiVisibleInDiffuseTransmission
00:00:00 ERROR | [mtoa.attr] Unable to create extension attribute .aiVisibleInSpecularTransmission
You'll keep getting that until a new Bifrost update is shipped. The current Bifrost doesn't have the bifrostGraphShape node yet.
And yeah, it's a bug that MtoA is trying to load it