Problem:
On certain Canon devices, toner supplies are not changing in level.

Reason: 
Short answer - Chip shortages

The ongoing global chip shortage continues to affect a wide range of industries. For example, printer maker Canon has had to resort to sending cartridges without chips inside. These chips are used to detect toner levels and to verify the authenticity of ink cartridges.

Chips will need to manually installed, and/or may have come off