with some models, soon after i send the print with cura to my printer and it starts printing, it ejects all filament loaded in the extruder. It seems to happen at about the same time on the same model. I have no idea why. I have also tried to change some settings, it still does it.

Check the Cura starting code. It’s probably extruding a few mm as a way of ensuring clean

flow. If that’s what it is, you can simply remove that line of gcode.