It seems that configuring it via cups and using the driverless option of discovered network printers gives the best results in printing quality.

Connected to the cupsd through https://localhost:631 in a browser:

Administration

authentication with root

Add printer

In "discovered network printers" section I get these 3 options:

HP LaserJet MFP M130fw (3330D5) (HP LaserJet MFP M129-M134)
HP LaserJet MFP M130fw (HP LaserJet MFP M129-M134)
HP LaserJet MFP M129-M134 (driverless) (HP LaserJet MFP M129-M134)

I chose the "(driverless)" one.

From what I understand the .ppd file should be created on the fly with cupsd communicating with the printer itself about its capabilities.

In /etc/cups/printers.conf I get at the end:

configuration made by hplip and using ppd described in the beginning of the thread:

<Printer HP_LaserJet_MFP_M129-M134>
PrinterId 6
UUID urn:uuid:54d8b569-230d-3b4b-6257-e384254c5030
Info
Location
MakeModel HP LaserJet MFP m129-m134, hpcups 3.23.5
DeviceURI hp:/net/HP_LaserJet_MFP_M129-M134?ip=192.168.1.223
State Idle
StateTime 1695995051
ConfigTime 1695022167
Type 36868
Accepting Yes
Shared Yes
JobSheets none none
QuotaPeriod 0
PageLimit 0
KLimit 0
OpPolicy default
ErrorPolicy stop-printer
</Printer>

<Printer HP_LaserJet_MFP_M129-M134_driverless>
PrinterId 8
UUID urn:uuid:5cb90984-e18c-32b4-4ca2-50fac32da52a
AuthInfoRequired none
Info HP LaserJet MFP M129-M134 driverless
Location unitedStates
MakeModel LaserJet MFP M129-M134 - IPP Everywhere
DeviceURI ipps://NPI3330D5.local:631/ipp/print
State Idle
StateTime 1696161542
ConfigTime 1696161247
Type 36868
Accepting Yes
Shared No
JobSheets none none
QuotaPeriod 0
PageLimit 0
KLimit 0
OpPolicy default
ErrorPolicy stop-printer
Attribute marker-colors \#000000,none
Attribute marker-levels 97,79
Attribute marker-low-levels 3,1

Attribute marker-high-levels 100,100
Attribute marker-names Black Cartridge HP CF217A,Imaging Drum HP CF219A
Attribute marker-types toner,opc
Attribute marker-change-time 1696161525
</Printer>

corresponding files under /etc/cups/ppd are quite different:

diff HP_LaserJet_MFP_M129-M134_driverless.ppd HP_LaserJet_MFP_M129-M134.ppd

1a2,4
> *%%%% PPD file for HP LaserJet MFP m129-m134 with CUPS.
> *%%%% Created by the CUPS PPD Compiler CUPS v2.4.6.
> *% (c) 2008 Copyright HP Development Company, LP
3c6
< *FileVersion: "2.4"
---
> *FileVersion: "3.23.5"
5a9,25
> *PCFileName: "hp-laserjet_mfp_m129-m134.ppd"
> *Product: "(HP LaserJet Pro MFP m132a)"
> *Product: "(HP LaserJet Pro MFP m132nw)"
> *Product: "(HP LaserJet Pro MFP m132snw)"
> *Product: "(HP LaserJet Pro MFP m134a)"
> *Product: "(HP LaserJet Pro MFP m132fw)"
> *Product: "(HP LaserJet Pro MFP m132fn)"
> *Product: "(HP LaserJet Pro MFP m132fp)"
> *Product: "(HP LaserJet Pro MFP m134fn)"
> *Product: "(HP LaserJet Pro MFP m130a)"
> *Product: "(HP LaserJet Pro MFP m130nw)"
> *Product: "(HP LaserJet Pro MFP m130fn)"
> *Product: "(HP LaserJet Pro MFP m130fw)"
> *Manufacturer: "HP"

> *ModelName: "HP LaserJet MFP m129-m134"
> *ShortNickName: "HP LaserJet MFP m129-m134 hpijs"
> *NickName: "HP LaserJet MFP m129-m134, hpcups 3.23.5"
8,14d27
< *FileSystem: False
< *PCFileName: "ippeve.ppd"
< *Manufacturer: "HP"
< *ModelName: "LaserJet MFP M129-M134"
< *Product: "(LaserJet MFP M129-M134)"
< *NickName: "LaserJet MFP M129-M134 - IPP Everywhere"
< *ShortNickName: "LaserJet MFP M129-M134 - IPP Everywhere"

....

with hplip configured one being hp-laserjet_mfp_m129-m134.ppd and the new and better one being ippeve.ppd (I presume created on the fly while configuring)

Gianluca