tag files at finder did not work well

I have multiple pdf files like 500 files inside one folder and sorted by tag only like "unsort","cpp","travel" tag and so on. sometimes i tag unsort to sort it later at free time. so later i reomve "unsort" tag and add "cpp" tag.

the problem is mac is creating a new tag like red,green,blue tag.

1- the files is shown under red tag

2- the file stuck and not got "cpp" tag

3- I can not delete "red" tag and stayed for days and even rebooting did not solve

kindly how to solve this problem.

Apple M1 Max

macos tahoe 26.2 (25C56)