Problem configuring the HP Color LaserJet Pro MFP 4303 to use only black toner when printing neutral grays

I am having a problem to configure the HP Color LaserJet Pro MFP 4303 to use only black toner when printing neutral grays, on computers with Ubuntu 18 and Ubuntu 22.

I'm using HPLIP version 3.23.12 (the latest currently available). On the HPLIP website, there is information that this model is compatible from version 3.23.8 of HPLIP.

The PPD file automatically found by HPLIP has options to define neutral gray prints using only black toner. But even using the options below

Text Neutral Grays: Black Only;Graphics Neutral Grays: Black Only;Photo Neutral Grays: Black Only

when printing a document with only black text, we notice that the printout is counted as colored by the printer, that is, all four toners are being used.

Does anyone have any tips on how to solve this, that is, how to use only black toner when printing neutral grays on this multifunctional?

Below is part of the PPD file that contains the neutral gray options.

*OpenUI *HPTextNeutralGrays/Text Neutral Grays: PickOne*OrderDependency: 57 AnySetup *HPTextNeutralGrays*DefaultHPTextNeutralGrays: Black*HPTextNeutralGrays Auto/Auto: ""*HPTextNeutralGrays Black/Black Only: "        globaldict /HPTextNeutralAxis known {            TonerBlack HPTextNeutralAxis        } if"*End*HPTextNeutralGrays ProcessBlack/CMYK Gray: "        globaldict /HPTextNeutralAxis known {            ProcBlack HPTextNeutralAxis        } if"*End*CloseUI: *HPTextNeutralGrays*OpenUI *HPGraphicsNeutralGrays/Graphics Neutral Grays: PickOne*OrderDependency: 57 AnySetup *HPGraphicsNeutralGrays*DefaultHPGraphicsNeutralGrays: Black*HPGraphicsNeutralGrays Auto/Auto: ""*HPGraphicsNeutralGrays Black/Black Only: "        globaldict /HPGraphicsNeutralAxis known {            TonerBlack HPGraphicsNeutralAxis        } if"*End*HPGraphicsNeutralGrays ProcessBlack/CMYK Gray: "        globaldict /HPGraphicsNeutralAxis known {            ProcBlack HPGraphicsNeutralAxis        } if"*End*CloseUI: *HPGraphicsNeutralGrays*OpenUI *HPPhotoNeutralGrays/Photo Neutral Grays: PickOne*OrderDependency: 57 AnySetup *HPPhotoNeutralGrays*DefaultHPPhotoNeutralGrays: Black*HPPhotoNeutralGrays Auto/Auto: ""*HPPhotoNeutralGrays Black/Black Only: "        globaldict /HPImageNeutralAxis known {            TonerBlack HPImageNeutralAxis        } if"*End*HPPhotoNeutralGrays ProcessBlack/CMYK Gray: "        globaldict /HPImageNeutralAxis known {            ProcBlack HPImageNeutralAxis        } if"*End*CloseUI: *HPPhotoNeutralGrays

Thanks guys