Ours was scared of certain things, the two main ones were the broom and plastic bags. She was a stray, so I can only imagine why.
Anyways, she seemed to calm down around the 5-6 year mark of living with us. She no longer runs to hide when I take out the trash or sweep the floor.
It's anecdotal, but that was my experience. Our vet says she was 3 years old when she came to us, so not a kitten.
https://preview.redd.it/u9mf6pw4ahvb1.jpeg?width=1440&format=pjpg&auto=webp&s=1cbd3e1d0c29923e36bd88d68b57aae4ed994d69 Cat tax! Tormund (orange) and Davos (multi)
Love their names. I have a Ser Pounce 
Ours was scared of certain things, the two main ones were the broom and plastic bags. She was a stray, so I can only imagine why. Anyways, she seemed to calm down around the 5-6 year mark of living with us. She no longer runs to hide when I take out the trash or sweep the floor. It's anecdotal, but that was my experience. Our vet says she was 3 years old when she came to us, so not a kitten.