There might be, using a service, but I am not sure whether it would solve the problem you experience. There are several bug reports on KDE multiscreen category, and this is one of them. When unplugging a monitor in Plasma session, all components (windows, panels, etc.) automatically move to the existing (primary?) monitor, while they won’t automatically move to the original monitor, if/when it is re-connected.
This looks like what is happening with sleep mode, in your case.
As I am not sure, and I am no Plasma user anymore, you might want to create a service to run the script, and see if it helps.
I installed Linux Mint with Cinnamon to test how things will be and my dual monitor setup is doing exactly the same.
When the computer goes to sleep and comes back from it, everything is messed up again...
Pages and apps opened on screen 2 are on screen 1... actually, everything is on screen 1.
So I don't think this is a KDE Plasma problem but something global with Linux or it might be something with my video card not sure but I did install Garuda Linux on my laptop(NVIDIA RTX 2060) and when plugged into a completely different 3rd monitor(different than my desktop setup), the same result can be observed.
This most likely means that it's not a KDE Plasma issue and it's not a video card issue. (My main PC card is Radeon 5600 XT), but most likely some issue with the Linux kernel? Or I don't know but unless this is fixed Linux is unusable for me from a productivity point.
Check your BIOS settings for a sleep mode, like S3 or similar, and alter/test other options. It could be that your vendor's default sleep setting disables external monitors completely.
Also consider disabling the Xsetup script in some of your tests, in case it has something wrong.
Frequently, using a different kernel can give different results with sleep functionality.
If it is possible, try hibernation, instead of sleep/suspend, to see if it works.
I have a dual-monitor setup that this happens to in KDE similar to how you describe, but in my case the two monitors awake from energy-saving mode at two quite obviously different speeds; the monitor that "wakes up" first is momentarily recognized as the only monitor and all open programs are (correctly) shifted to that workspace. The second monitor wakes up a moment later and starts off with an empty display.
I've never looked into it too much because it has never bothered me, but I guess if you want to use the energy-saving mode and preserve your display configuration, maybe you should investigate how to get both monitors to return from energy-saving at the same time.