Mini Thermal Printer missing pixels dull printing

I just got the Mini Termal Printer, had some troble to get the paper and I am just now testing with the python library
All printouts are feeble and weak. I tried do increae heating time but had no success.

Due to logos are printing it must be the correct printer, but changing the heating prameters does not help.

Is it another dialect of printing? A different firmware ?

May it be the paper? Is it faulty?
in this case i would expext printing parameters have influence on the print, it should get weaker…
The prints identical lines for each value

Product: COM-B004
Firmware: GV2.16.08 20180627 (as far as readable)
Connected via FTL232 Adapter 5V to Linux Workstation

Thanks to Piromoni!

They sent me a new printer which ist printing without errors. It seems to have been a defective unit.

See attached picture, Power Supply at 5V current approx 1.7A, limited to 2A

Even Esc 7 n n n seems to work

Many Thanks to Piromoni Support.
I posted the Picture and Problem here and asked for a solution via mail.