AC Heater flicker light when heating up the bed.
In the heater section of Klipper printer.cfg add below code, this should reduce or remove flicker.
Save and restarting configuration and try bed heater again.
Back up Klipper Configuration
Once printer is calibrated we highly recommenced saving your configuration locally to your computer, as configuration saved onto raspberry pi sd card is not always reliable and depending on SD Card you may loose your configuration due to SD card corruption or failed sd card.
A helpful checklist video by Nero 3D
Klipper Voron Pressure Advance Tuning by Nero 3D