Safari Tab Label issues

Go step by step and test.

1. Click  in the menu bar and choose “Force Quit”.

Select Safari and click “Force Quit at the bottom of the Force Quit window.

Hold the Shift key down and launch Safari.

2. Empty Caches

Safari > Preference > Advanced

Checkmark the box beside "Show Develop menu in menu bar".

Develop menu will appear in the Safari menu bar.

Click Develop and select "Empty Caches" from the dropdown.

3. Remove Cookies and test.

Safari > Preferences > Privacy > Cookies and Website Data...:

Click the “Manage Website Data” button.

Remove all cookies except ones from Apple, your internet service provider and banks.

This will take awhile. Please be patient.

4. Disable Extensions and test.

Safari > Preferences > Extensions

Select and disable all extensions and test.

Enable Extensions one by one and test.

To uninstall any extension, select it and click the “Uninstall” button.

If the above doesn't work try deleting the cache.

Go to Finder and select your user/home folder. With that Finder window as the front window, either select Finder/View/Show View options or go command - J. When the View options opens, check ’Show Library Folder’. That should make your user library folder visible in your user/home folder. Select Library/Caches/com.apple.Safari/Cache.db and move it to the trash.