Short answer (search yourself on this forum or ask your AI companion making us old guys obsolete ).
This message indicates the internal counter is at 100%.
You can find on eBay hacks for the Canon service tools.
Verify if the tool is recent enough and your printer is supported if not it locks the printer for further resets.
Most probably the ink absorbers themselves are not full and you can continue to use the printer for a while.
Dismantling the printer is quite difficult.
You find a service tool here that is suitable for your printer. Here is an instruction for doing the absorber reset. Do not use the service tool v3400 as it will lock access to service mode but instead use the v6220 from eBay. The procedure for doing the reset is the same.
Even if the printer most likely will not leak if you reset the counter and continue printing, it might be a good idea to put a shallow tray under the printer to contain a possible ink leak. Only reset the counter once and continue printing without replacing or washing the ink absorbers,
Some new Canon printers of Megatank G and GX series have a user replaceable maintenance (=ink absorber) cartridge. See this video.