As stated here, metatables should be allowed to be removed from types in the New Type Solver. I did some research before and normally one would call setmetatable(t, nil) on regular variable to remove the metatable at run time but setting the type as setmetatable<mt, nil> does not remove it at all. Code example:
type original = {}
type meta = setmetatable<original, {}>
type new = setmetatable<meta, nil> -- Type Error: Type function instance setmetatable<meta, nil> is uninhabitated