Help!! Why is my baby struggling during her nighttime bottle??

My daughter is 4 months old. She sleeps through the night (about 11-12 hours). I feed her 5 times a day (every 3ish hours). She gets 2/3 formula and 1/3 frozen breastmilk (from when I was pumping). She's always been fine with that. Never cries or fusses and drinks the whole bottle. But over the passed week or so, her last bottle of the day (around 8pm) she screams and refuses to eat! Like as soon as I sit down and touch it to her mouth, she takes a sip and then screams! She cries and cries and doesn't want to eat! I've begun to dread this last feeding. I don't believe it could be her formula or breastmilk causing her to cry, since she takes all other bottles fine. No other factors change for her last feeding that would cause her to do that only for the last bottle! I don't get it. I read about "witching hour" so I tried to give her more sleep during the day. But she's still screaming. Sometimes I think it's gas, but could it really just be gas every single night? It would take me an hour or more of just trying to comfort her to get her to eat. I've even prepared bottles with just formula and she's still doesn't do much better. I really don't know. Maybe I will try a different formula or call the pediatrician. I really don't want to because I have 2 more tubs of this formula, and because it's just at night, so I couldn't imagine the formula being the problem. Ugh. Anybody have advice? It's such a strange thing for a baby not want to take a bottle at the same time every day.

Edit: Thank you all for your suggestions! I felt kind of stupid posting this question. She's my second baby and I feel like I should know how to take care of a baby and know what my baby wants. But you all were so kind in your responses, and I'll try some of the stuff you all suggested!