Hi, I had the same issue (Debian testing with KDE Plasma).
I found a workaround after reading those links : https://discuss.cachyos.org/t/powerdevil-related-errors-when-trying-to-access-i2c-error-eacces-13/10233 and https://wiki.archlinux.org/title/Udev#Allowing_regular_users_to_use_devices (see note) Create this file to override existing udev rule(*): sudoedit /etc/udev/rules.d/69-i2c-permissions.rules with this content: SUBSYSTEM=="i2c-dev", KERNEL=="i2c-[0-9]*", MODE="0660", GROUP="i2c", TAG+="uaccess" (*) /usr/lib/udev/rules.d/60-i2c-tools.rules provided by i2c-tools package -- Bruno
