To reproduce:

1. Create a new template using the "Docker Containers" starter template (notice it does not allow customizing the autostop and has a default of 24 hours).
2. Create a workspace using that template. The workspace must be created while autostop is currently enabled. Workspaces that are initially created with autostop disabled somehow do not have any problems updating correctly.
3. Disable autostop in the template through the UI.
4. Update the workspace, notice it will continue to say "stops in a day" despite autostop being disabled in the template, and showing as disabled in the workspace settings.
5. New workspaces are fine and do not have any autostop.

I think the default autostop gets set on the workspace, but when you disable autostop it does not then remove it from the workspaces, and you cannot change it as a user either because autostop is disabled in this scenario.