Appraisal of calligraphy and painting needs a professional eye. Only professional knowledge can be firm. It depends on the eyesight. There are too many fakes now.
Xu Linlu, Zhang Jincai, Mi Jingyang and the late Wang Dashan are authoritative critics of Qi Baishi's works.
Xu Linlu once told a secret to identify Qi Baishi's paintings: when the old man Baishi painted, ultramarine was never used in the paint.
Zhao Yu, a well-known expert in cultural relics appraisal, believes that the appraisal of Qi Baishi's works should be comprehensively evaluated from the aspects of brushwork, style, charm and so on, and what kind of seal Qi Baishi's works should be carefully researched.
The old man Baishi came up with some strange tricks before his death. For example, when he was 87 years old, he quietly wrote the word "mouth" under the word "stone" in a circle until he was 92 years old. It was not until the counterfeiters found out that the word "mouth" was reduced to a square.
When the old man Baishi was 75 years old, he was 77 years old from the age of two. If there is 76-year-old handwriting in the inscription of Qi Baishi's works, it is forged. On the stamp, the old man Baishi first carved a "Qi Baishi" steel seal and put it on the painting. Later, he found that someone had stolen the steel seal, so he pressed it with his finger and left his fingerprint. For masterpieces that need to be treasured, the old man also tried to raise the original stamps with some skills.
I hope the answer can help you.