Fullscreen URL param no longer works

[cbake886]

Kibana version:
8.10.4, 8.11, 8.12
Elasticsearch version:
n/a
Server OS version:
Linux
Browser version:
Chrome 120
Describe the bug:
I have a client that utilizes Elastic for various high level reporting and dashboarding tasks. Recently we migrated them over to 8.x versions but now the &_a=(fullScreenMode:!t) URL param to have their Dashboards go to full screen by default is not working. This was working prior to 8.x Kibana
Steps to reproduce:

1. install / load up kibana 8.x+
2. go to a dashboard and add &_a=(fullScreenMode:!t) to the end of url
3. Does not go full screen

Expected behavior:
adding &_a=(fullScreenMode:!t) to the end of url should make it go full screen
Screenshots (if relevant):
n/a
Errors in browser console (if relevant):
none
Provide logs and/or server output (if relevant):
none
Any additional context:
this is used by many large corps to have the default route for a space to auto load into a full screen dash.

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)

[Heenawter]

Looks like this problem dates all the way back to the portable dashboards work - tested on that PR and the fullscreenMode param didn't work; tested on the PR that came right before that one was merged, and it worked.

[cbake886]

Is there an ETA on when a fix will be in place?