Sounds like a feature, not a bug. You can tell when your toner runs out when it prints light.
That reminds me of this cartoon about doing things manually when computers are down.
https://www.reddit.com/r/funny/comments/a8nta/our_computers_are_down/
One gets more exercise that way.
It is a cool racket. Sell a decent ink-jet with some attractive features for $150 or so, then charge $40 or more for a simple replacement cartridge,