Hi, the problem is probably with the weights. but there are some issues with your mesh modelling.
Without the file or screenshot of the wireframe and weights its hard to know.
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I was able to solve this problem by selecting the vertex group associated with the bottom lid blink shape key and separating by selection by pressing ‘P’ then rejoining the objects by selecting the bottom lid and the face in object mode then pressing ’ CTRL + J’ to join the objects.
No more jittering.
I didn’t use weight painting and the mesh is symmetrical, I think it has to do with the basis and the top lid blink somehow being affected by the most recent shape key i made which was the bottom lid blink