No major antagonist introduced in S3, major antagonist for S4 revealed almost half-way through and it's someone who already jobbed, off-screen, in an earlier season.
Undercutting of previously established themes such as responsibility, independence, freedom, and trust for racism, multiculturalism, midlife crises, and love triangles.
Character flanderization, assassination, and belying previous set-ups for "subversion".
Incoherent plot and poor pacing resulting in inconsequential events taking up air time, while major details are rushed or resolved off-screen.
Lack of comedy for a comedy show; previous seasons had about a gag every ten to twenty seconds, either in the foreground or background, while now they come at about one per minute, if that.
Lack of interaction with the audience, whether it's the live in-character Q&A's or posting information in general, as the team prefers to talk with each other over social media and pat each other on the back for adding self-inserts or pushing agendas rather than interact with fans.
Yadda yadda yadda...