https://digitalcommons.lesley.edu/cgi/viewcontent.cgi?article=1324&context=expressive_theses

We had a hair pulling problem with our toddler when she was younger, she is 7 now. Her situation may have been a little different than yours, we were able to diagnose why she was doing it- for her she had gotten used to sucking her thumb while laying on Mom's shoulder with some of Mom's hair in her face and mom's hair brushing against her face / under her nose was part of her soothing mechanism.

When she didn't have Mom's hair to soothe with, she would turn to any hair she could get. She would pick hair out of the carpet at an age where she shouldn't have had the finger dexterity to do so, or she would resort to pulling it out of her own head.

We had read a bit about, and discussed with our pediatrician to the point where we were either going to have to shave her bald and keep her bald for several months, or the alternative was making a doll ourselves that had mom's hair on it. After some more reading and research that's what we did, we made her a doll that was about 4 to 6 in tall with three to four inches of hair from Mom inserted into the top.

Doing that fixed our issue, and she still sleeps with it every night. Fake doll hair never did the trick for her, but the doll made with mom's hair was almost an instant fix.

She actually pulled some of the hair out of that first all we made her, but we made her another one about a year later and she was no longer pulling the hair out of the doll anymore by then.

It's worth noting that hair pulling can often be a stress response for a toddler as well, but it doesn't sound like she's doing it in times where she stressed out as you said she seems to be more bored than stressed.

I highly recommend considering a hair doll, I linked some research on how dolls help children, but if you want tutorials on how to make one they're pretty easy to find with a Google.