It’s Methotrexate. Even if you take folic acid you can get hair loss. Talk to your doctor and get off of it ASAP. You will still need to continue taking folic acid. It takes weeks to get it completely metabolized and out of your body. I was constantly thinking hair loss is from RA itself, from steroids, Covid, stress. I was devastated. Then I had to get immediately off of Methotrexate , without weaning due to pulmonary complications of Methotrexate . My hair started to grow back. At one point my scalp was full of new, baby hair. My new hair is coarse and curly now, but I am so glad I’m not bolding anymore!
Methotrexate is not for everyone. Talk to your rheumatologist ASAP

Methotrexate made my hair thin terribly.

My daughter (a teen) is taking humira and methotrexate for RA, her hair is also falling out. She's only been on the medication for 4 months. She's also experiencing nausea and a significant weight loss.

I took methotrexate when I was first diagnosed. I, too, lost hair and the texture changed so much I ended up cutting it short. Luckily the doctor took me off of it because it was causing liver enzymes to elevate. Now I take Plaquenil daily and Embrel shots once a week. Hair didn't really grow back, but it's healthy again. Talk with your doctor about a change of medication if it gets too bad.

I've gotten some hair re-growth from hair, skin, and nails gummies