Oh, sorry. Turns out I can't find that option either... I will fix it in a future update.
But try this temporary fix:
https://mega.nz/file/JJpVSAZb#0TVfJ4nRBHSp0Sh6_cD_qi5ETmHFurJY-6M-l6U0ntY
If you extract that file to GoblinLayer/www/js/plugins, I think it will disable the light effects.