Comment 11 for bug 1699484

...and the problem can seemingly be avoided by hacking src/server/graphics/nested/platform.cpp to ignore the size of the buffer:

    bool passthrough_candidate(mir::geometry::Size /*size*/, mg::BufferUsage usage)
    {
        return connection->supports_passthrough(usage) /*&&
            (size.width >= mir::geometry::Width{480}) && (size.height >= mir::geometry::Height{480})*/;
    }

(And no, I don't know what those magic numbers are for.)