The page is all messy and not clear (gray color).

None. It is electrostatic attraction.
It varies from each type of laser printer.
Most printers will specify a total number of pages printed from a laser toner cartridge rather than give an actual amount of toner per page. Which I feel would be more likely to be an average value.
Due to the amount of toner being used per page varying on the number of actual pixels that are required - a black dot or a color dot. If a colour dot is required Three toner colors may be involved to get the color required. Where there is a white dot no toner is required.
It really depends on what image is being rendered onto the paper on each different page image print onto the paper.
Color photos use more toner as more of the page is color than when using black and white !

Sounds like defective capacitors on the power board

lost the manual; it as clear vision mode try that yete/
no photos posted of ugly screen makes answers crazy hard.

The PC is set to 1080P , monitors do as they are told , only
the monitor has data sheet and manual tells all resolutions it can do
and same with the MAC, but no full MAC model told or GPU options there. matter most.
HTMI PC to MON DVI
or
DVI PC to MON HDMI
??????????
many adaptors like that are super poor to horrid but work.
ont this monitor page 50 shows 1080p is max on mon HDMI.
see that. I guess the MAC is DVI:"?>?????
I can not understand this statement
Connection is HDMI to DVI.
the monitors have sub codes in the model to tell us if it has 1 2 or3 video inputs, I can not guess yours
but it is sold, vga ,dvi and HDMI version. for sure.
the monitor is as old as 2011.
VGA can do.

here is all the monitor can do
on this page of your monitor

https://www.manualslib.com/manual/567507/Aoc-I2353ph.html?page=50&term=vga&selected=1#manual

It tops out at 1080p
try the clear vision mode

if the monitor looks ok on a 2nd good PC
then the mac has problems.

The printer doesn't use ink, it uses toner, a black powder. The toner is then pushed onto the page using magnetic force and fused to the paper using a laser. Which replaces the traditional "ink injection" method.

The toner cartridge is a black unit that pulls out located behind the top access panel in the front. This unit contains a glass drum and behind it a well of toner powder. Usually you have to replace the entire unit.

There are toner cartridges with plastic caps which can be removed and then refilled with the powder. However, this powder is messy, difficult to manage, and eventually the drum will become scratched and worn since it is not really designed for prolonged use. So I recommend just replacing it.

While the toner cartridge will run more than ink. The frequency with which you have to replace it is significantly less. So while ink can run you as much as $0.25 a page when you factor in the wear and tear on the printer. Laser printers are more along the lines of $0.04 a page.

If you replace the toner, read the directions carefully and be sure to remove the plastic shipping strip from the side of the cartridge. This strip is used to hold the toner in the cartridge while it ships and will keep it from working properly.

I would say the crt's are at the end of their life.

It sounds like you have a developer housing failure.

Maybe you have some dried ink on the cartridge. You see the silver-ish strip on it? try whipping it down with a rag because I dont think you want that ink on your shirt. Try that and if not let me know.

-Ryan

-Please rate

the toner cartridge is near to empty so the powder collected on the wastage side is getting leaked when ever you give a printout and that leaked powder creates a line on the paper. or there is a dust collected in the lower area of the printer by the leaked tonner. replace the cartridges or get refilled it properly.to make this problem clear.

there is no going back, you have chemically changed the powder coat composition. Learn your lesson well and next time use a H-D listed cleaner and a very soft brush.

Does your scanner software give the option to choose different modes...grayscale, color, black & white?? This sounds like it's scanning in grayscale....if you can change it to black & white, the background should remain white.