Unable to set run_current without triggering weird behaviour

[Givemeurcookies]

Hello, I have upgraded my Creality CR-10 with the Manta E3EZ and EZ2209 and got everything working.
I however had issues with all the steppers overheating (i.e the extruder melts the PLA when trying to extrude)

Based on the documentation I have to adjust the run_current in Klipper to have the EZ2209 driver limit the current to the steppers.
This is where I got some weird behaviour when setting the run_current in Klipper, if I set (taking the x motor as an example):

[tmc2209 stepper_x]
uart_pin: PB8
# diag_pin: PC4
run_current: 0.800
stealthchop_threshold: 999999

After setting this config the stepper on that axis moves about 50% of the distance when homing compared to when the configuration isn't set + there is more coil whine and the steppers move really slowly. In addition, after some debugging makes it seem like changing the uart_pin: PB8 doesn't have any effect. Is this the correct pin for UART for the x stepper? It almost seems like when the default values set the uart_pin to the correct values.

If I comment out the config above, the steppers suddenly behave as expected but then I have the overheating issue again. Even if I set the stepper run_current to the max 2A it doesn't make difference.