[Disable M105?]

If you set temperature settings by yourself in printer profile start gcode, cura won't use that template it prints before the start gcode. You'll need to use replacement patterns to do that.

 

M140 S{material_bed_temperature}   ; set bed temp
M190 S{material_bed_temperature}   ; wait for bed temp
M104 S{material_print_temperature} ; set extruder temp
M109 S{material_print_temperature} ; wait for extruder temp

 

Because it's not using the template to add temperature codes, it'll also skip M105.

Here's an example how this start gcode rendered:

 

;FLAVOR:Marlin
;TIME:2429
...

;Generated with Cura_SteamEngine 4.12.1
M82 ;absolute extrusion mode
; Ender 3 Custom Start G-code

M140 S60   ; set bed temp
M190 S60   ; wait for bed temp
M104 S200 ; set extruder temp
M109 S200 ; wait for extruder temp
G92 E0 ; Reset Extruder
G28 ; Home all axes
G1 Z2.0 F3000 ; Move Z Axis up little to prevent scratching of Heat Bed
...