Is this much hair coming out after brushing normal?

recently my hair has been falling out soooo esp when brushing. I have pretty long hair and pretty healthy. I rarely use heat, use protein treatments & oils treatments. my hair holds styles well so I let it air dry & I don't brush it for a few days, it's also been in a bun 90% of time bc it's really hot. could it be since I'm not brushing every day its just all the hair That's supposed to fall out. I'm wondering if this is normal amount or if it's something I should get checked out.