A steep list of problems growing with the day

Well hello there. some might have seen earlyer questions the past days but im getting tired. im putting 12 hours a day into this machine and it didnt give me a second good print ever.

First the machine didnt print at all directly trew a error now thats solved i though i can start the first print finally.

the first print came out okay using a silk gold and normal silver pla the change it color wasnt on the spot but as i read it was a learning thing from the machine

The second print failed and another one failed all failed

first one was different the splice broke in the machine so i tuned the splice and now all filament is correctly and not breaking.

All further prints all fail on the same stupid problem. as soon as the first color changes into the second all goes down hill.
it seems its underextruding quickly and for example the keychain the first outline goes good then the first layer infill good then its fully underextruding just small blobs end up causing a color shift and not resuming normal print when i take a look its grinding
I tried a single color print from my octoprint setup same model and no underextrution is happening so it must be the P3Pro.

or canvas slicer im trying lower speeds i normally print at 30-40 i already tried 35 and 30 mm both same problem no change

i already wasted almost a entire roll of fillament when combining the different colors and such and its getting harder and harder to spot the problem.

i have a Ender 5 Plus with bowden extruder setup with the stock hotend but a special wear resistant nozzle (brass with nikkel coating)

I only use PLA the normal Silk and GID variant. even when i use normal just normal the problem occeurs.

if anyone has stuff i can at least try im out of ideas and it already is a major expense for me. im already thinking if i should replace my extruder with a direct drive al tho i dont know if it solves these issues.