I’m currently developing a 2D platformer and chose to use cinemachine dolly tracks to follow my character since I posted a question about a problem using confiners that got lost into oblivion: 2D Cinemachine weird behavior for non rectangular confiner - Questions & Answers - Unity Discussions.
I was using Unity version 2019.2.12f1 and didn’t have any issue with that, but when trying to use timeline for some cutscenes I found myself in need to update to 2019.3.7f1 due to some bug that was fixed in this version and started to notice the problem, so I updated cinemachine to version 2.5.0 and things got even worse.
I tried following the “solution” here: Dolly camera stutters instead of moving smoothly with no success.
I tried increasing the path resolution to max, increasing the search resolution of the camera, changing damping, changing the position units to normalized and nothing seems to work.
I uploaded a video to show the issue
Again this only started to happen when uploading my Unity version, everything was fine with the previous one I used.
I’m sorry that no one answered your post on Unity Answers. I don’t monitor that, so can’t really say why.
You can create odd-shaped polygon confiners if you use CompositeCollider2D as a bounding shape.
One common gotcha when using 2D confiners: the confining shape not have any parts where the shape is too small for the camera frame to fit. If that happens, you will get strange camera popping when the confiner tries to fit the frame there. Always make sure that the shape is big enough to hold the camera, everywhere.
As for this post, I’m not really sure what behaviour you’re trying to fix. You’re randomly changing settings in the video, I don’t know why. I will hazard a guess here.
You have to be very careful with your path shape when using auto-dolly. The follow algorithm just tries to find the point on the path that’s nearest to the target. It’s not appropriate for all path shapes. If the path shape moves in an arc around the target (as it does in your video when the character is jumping), then the “nearest” point can be very noisy. You can calm that down by increasing the Z-damping in the Tracked Dolly:

As an extreme illustration of the position noisiness, imagine a perfectly circular path going around a target placed at the center. Where is the “nearest” point on the path? What happens if the target moves back and forth, even slightly? The “nearest” point will go crazy.
Is the dolly path the best choice for you in this situation?