Inkjet ink levels [ in all ink jets i should think]
as displayed on the screen have no relation to the actual ink content in the cartridge.
There is no electrical connection feeding this data back.
What happens is that the printer software 'looks'
at the sheets of paper consumed and does a 'guesstimate'
The user can then keep on printing until the ink fades - which, depending on the type of work undetaken could be many 100,s of sheets or may be only 50 or so, after the 'Low Ink' warning.
Buy the next cartridge and load only when you get a 'bald' sheet delivered.