MasterClass brings you close to recognized greats, but to an extent your learning will be more about _them_ and only tangentially about the field of interest. There are some MasterClass episodes conveying very practical knowledge - typically the cooking ones - but again I'd call this a different thing than really learning about cooking (theory, law, etc).
Systemically understanding a field of interest is a different endeavor requiring more rigor. The Great Courses product is probably the more rigorous (categorically similar) educational tool in comparison to MasterClass. It has less production value (though more than sufficient) and the lectures are from obscure though academically recognized authorities rather than curated celebrities.
_IF goal is to:_
Really learn a new field or skill during the pandemic = The Great Courses.
Watch autobiopic on recognized authority = MasterClass.
For the record, I have both and am affiliated with neither.