Greetings

Running a AMD 3800X with a Radeon RX570X graphics card using
opensource amdgpu drivers (version compiled for 1.21.1.3, module
version = 22.0.0, Module class: X.Org Video Driver, ABI class: X.Org
Video Driver, version 25.2) running xorg-server 2:21.1.3-2+b1.

I think my system is reasonably upto date running Daedalus. (Last apt
update check done this morning.)

The issue - - -

After a system reboot the screens will enter screensaver pretty
picture mode and then blank to off at the chosen times. I've got 5
monitors set up to display most of a 7680x3000 virtual desktop.
Also run a lot of desktops and tend to accumulate a lot of tabs in my
browsers. Run at least 3 browsers at once (Opera, Brave and Firefox)
with Firefox as the default and have in the past also run Vivaldi.
Firefox is the default browser.
Firefox is the only browser that will place its windows where I had
them on the various desktops. Finding this I have reduced every other
browser to windows on at most one 'desktop'. That is the only way that
I can get any time at all where the screensaver just does its job.
The problem is that after about 80 hours (or so - - - - haven't
defined that time with any precision) the screensaver will move to the
pretty pics screens but does NOT move to screen off.

I have been trying to find what in either the browsers is hindering
the screen 'blanking' (if I'm using the correct term) or is breaking
on my system - - - dunno. Have been looking at xset as well but really
don't know what the bleeping blazes I'm doing and don't want to create
an even bigger mess!
I am using lxqt still on version 0.16.0 trying to wait patiently for
version 1.01 which is supposedly going to move from experimental to
unstable and testing hopefully very soon but that timing is NOT up to
me.

Is there someone out there in Devuan land who has any idea of how to
change this annoying behavior?
Can I change something in Xset to make this happen?
Something else?

(I can reboot and set up things the way I want (takes about 1/2 hour
in total to do everything) so I find that this time every 4 days is a
nuisance. )

TIA