As I'm sure you're aware, the vast majority of us absolutely do NOT want the screensaver to come on while OBS is running, so I would not be surprised if it was just hardcoded and left that way. In fact, most of us would see your demo and call it a bug that it allowed the screensaver to run at all.
It's VERY rare for someone to *want* to capture a screensaver unless they were specifically demo'ing it, in which case it wouldn't be too hard to have two separate machines: one to run the screensaver and the other to capture the physical video signal.
If you *want* that effect, then most of us would not think to use the screensaver, but instead to try and recreate it with something that doesn't depend on activity. Maybe a screen capture for each desktop, with a cube-rotate transition between them?
Set up OBS to automate that sequence of scenes, and have a hotkey to start and/or stop it. (switch scenes, into or out of the loop; duplicated scenes are okay too, with one in the loop and the other not) The
Advanced Scene Switcher plugin will likely come in handy for this.
Oh, and update OBS from v27 to v29. The modern version of Adv. SS needs v28 or higher because of a massive graphics change between v27 and v28, that breaks compatibility in both directions. The v27 version of Adv. SS is only supported by special request, and is therefore far behind now.
Make sure you update ALL of your plugins at the same time, and explicitly save their settings before you start the process. Screenshot if necessary. Anything that doesn't *immediately* survive the upgrade will have to be rebuilt from scratch or from what you saved.
