This is one of the (many) reasons why I've started using Phoenix LiveView for all the projects, when I can, that need either partial or full client-side functionality.

By simply keeping all the state, logic, and rendering on the server, all sorts of issues are avoided and various optimizations are possible, and I get full server-side rendering for free!

The client-side, meanwhile, via websockets, only sends events to the server and diffs whatever chunks of markup are sent back. Most of this is via server-side provided attributes (phx-click, phx-change, etc.), but for the slightly more 'exotic' stuff I can add my own events.

Obviously there are cases where this solution isn't practical, but this hasn't been the case for the vast majority of my projects.