Lighthearted really, although I can't stop worrying about the amount of things my 1 year old is afraid of!
The biggest day to day worry for him is ceiling lights! This started a couple of months ago and hasn't gone away yet. We show him how they switch on and off and he seems to even enjoy this sometimes but at other times he can be happily playing and then look up at the light fitting (on or off) and get really upset. When I am carrying him and he is higher up so closer to the lights he clings on to me for dear life. He has started shows signs of being afraid of light fittings when out and about too.
He is also afraid of noises when he can't detect where they are coming from (for example, the sound of the ice cream van outside or when I talk to Alexa and it talks back- I've stopped doing this).
What unfathomable things are your babies afraid of? For those who have been through it, please tell me this will pass. I can't make light fittings go away unfortunately!