It seems that when the line test=model.predict([text]) is executed, your entire project runs six times consecutively, and when you close the opened windows, it makes predictions.
You can see the code snippets below.

[main file]

print("test1")
def classification():
    print("test2")
    raw_text = str(entry.get("1.0", tk.END))
    tahmin_sonucu = main(raw_text)
    categories_label.config(text="Kategoriler: " + tahmin_sonucu)

[main function]

from simpletransformers.classification import ClassificationModel

labels = ["Bilim Kurgu", "Ekonomi", "İslam", "Polisiye", "Romantik", "Sağlık", "Spor"]
model = ClassificationModel('bert', 'bert_model', num_labels=7, use_cuda=False,
                                    args={'reprocess_input_data': True, 'overwrite_output_dir': True, 'num_train_epochs': 3,
                                        "train_batch_size": 16, "fp16": False, "output_dir": "bert_model"})
print("test11")
def main(metin):
    tahmin = None
    print("tes12")
    tahmin=model.predict([metin])

    print(labels[tahmin[0][0]])
    
    return labels[tahmin[0][0]]

Outbut