In case of absent or insufficient ambient light, you can adjust the lighting brightness inside the enclosure of J1 during printing to better observe the printing process of the on-going task, according to your actual needs.
Once set, the brightness data will be saved for future printing processes and will remain effective even after the printing until you adjust it again.
Updating new firmwares after V2.5.9 will not reset the brightness data, while rolling back to versions before v2.5.9 will reset it.