Best score can not go up to a high level

[SHarkbingowo]

when I train this model in a new dataset;
the Loss go down fast and converge to a low level.
however the Best score can not go up to a high level.
what's matter

2022-09-19 03:18:33,715 - INFO - Epoch: 14, Iter: 64930, ETA: 0.01 hours, lr: 0.000014, Best_score: 54.07 | loss_cls: 0.00848, loss_reg: 0.00295, loss_tir: 0.00000, loss: 0.01143
2022-09-19 03:18:43,777 - INFO - Epoch: 14, Iter: 64940, ETA: 0.01 hours, lr: 0.000014, Best_score: 54.07 | loss_cls: 1.61902, loss_reg: 0.00666, loss_tir: 3.01662, loss: 4.64230
2022-09-19 03:18:54,033 - INFO - Epoch: 14, Iter: 64950, ETA: 0.01 hours, lr: 0.000014, Best_score: 54.07 | loss_cls: 0.01017, loss_reg: 0.00298, loss_tir: 0.00000, loss: 0.01315
2022-09-19 03:19:04,120 - INFO - Epoch: 14, Iter: 64960, ETA: 0.01 hours, lr: 0.000014, Best_score: 54.07 | loss_cls: 0.00803, loss_reg: 0.00293, loss_tir: 0.00000, loss: 0.01096
2022-09-19 03:19:14,176 - INFO - Epoch: 14, Iter: 64970, ETA: 0.00 hours, lr: 0.000014, Best_score: 54.07 | loss_cls: 0.05333, loss_reg: 0.00409, loss_tir: 0.00000, loss: 0.05742