the HTTP response for displaying a workflow instance contains all global form rules.
It's ignored which kind of form rules are used by the process/element.
The response should only contain those form rules which are referenced. After all, the exported process will also export the used/referenced global form rules and not all.
This applies at least to versions 2023.1.2.44 and 2022.1.4.155.
Moving these form rules out of the HTTP response for each element would have an even bigger impact. Although I have to admit, that I have no idea how new versions of form rules would 'update' the old version on the browser.