This is an issue that happens on multiple versions (known issue in ATM7 even) but I did not see it reported for ATM9

Builders upgrading houses will disturb lanterns causing fires that destroy entire houses. Probably not a good default config.
To disable the feature set the below config to either OFF or NO_FIRE.

I suggest setting either as the default to avoid players experiencing these seemingly random fires!

config/supplementaries-common.toml

#Allows ceiling lanterns to fall if their support is broken.Additionally if they fall from high enough they will break creating a fire where they land
		#Allowed Values: ON, OFF, NO_FIRE
		falling_lanterns = "ON"