I often have a hard time placing the exact episode, in which The Simpsons jumped the shark, but for me, the "22 Short Films Abount Springfield" episode [0] in season 7 was the first one I distinctly remember having mixed feelings about, while watching it.
By the eighth season for sure, there was even in-show acknowledgement, that the characters were becoming over-developed and being painted into unimaginative corners by established and beloved continuity, while simultaneously being victimized by groupthink, in the Poochie episode [1]. That was probably the last "good" episode, in my humble opinion.
Also, in season 8, with the airing of the Guatemalan Insanity Pepper episode [2], I found that more episodes were frequently disappointing and unfunny, including that episode, and I tuned out.
[0] https://en.wikipedia.org/wiki/22_Short_Films_About_Springfie...
[1] https://en.wikipedia.org/wiki/The_Itchy_%26_Scratchy_%26_Poo...
[2] https://en.wikipedia.org/wiki/El_Viaje_Misterioso_de_Nuestro...
By the eighth season for sure, there was even in-show acknowledgement, that the characters were becoming over-developed and being painted into unimaginative corners by established and beloved continuity, while simultaneously being victimized by groupthink, in the Poochie episode [1]. That was probably the last "good" episode, in my humble opinion.
Also, in season 8, with the airing of the Guatemalan Insanity Pepper episode [2], I found that more episodes were frequently disappointing and unfunny, including that episode, and I tuned out.
[0] https://en.wikipedia.org/wiki/22_Short_Films_About_Springfie...
[1] https://en.wikipedia.org/wiki/The_Itchy_%26_Scratchy_%26_Poo...
[2] https://en.wikipedia.org/wiki/El_Viaje_Misterioso_de_Nuestro...