This friend and I have known each other for five years, when we met during an outing to study, at the beginning she was particularly warm and straightforward, making people feel very comfortable.
Then she got into the civil service and moved to my city, and we had more chances to see each other. But I slowly realized that she was no longer as polite and courteous as she used to be when we met occasionally, instead she started to pick on my shortcomings, and her way of speaking changed from blunt to a little aggressive.
She can be quite mean and a bit overwhelming when it comes to behaviors she doesn't see eye to eye with.

I'm quite sad because my best friend has become a completely different person than before, as if he's a different person.
One even had the urge to avoid her, not wanting to be in close proximity again.
So how the hell am I supposed to get along with her?
When one's status, wealth or honor is elevated, many people change. If your own status and wealth haven't changed much, and you're still the same person, you may not be able to get along with your changed friends as easily as you used to.
I'll tell you a true story: there are a group of organizations working buddies, usually used to call each other old Zhang Xiao Wang. Later, the old Zhang was promoted to become a section chief, we congratulate or call him old Zhang, he was reluctant, must be called Zhang section chief, the scene was once very embarrassing ...... results of this group of friends no longer mention "Zhang section chief".
In your case, your friend probably feels "superior" to you, and this mentality makes her think that she is superior to you, so she treats you this way. What is the point of having a friend? You need to think about this first, and then re-evaluate your relationship to see if it's necessary to stay close, and if distancing yourself from her will have a negative impact on you before deciding whether to continue to see her on a regular basis.
I believe that a truly good friend should lend a hand when the other person is in trouble, not elevate themselves by putting down their friends, who are not meant to be used or hurt.