Update from 3.9.6 to 4.0.x breaks select2 search field

After update from 3.9.6 to 4.0.x it is necessary to manually reload/clear browser cache, otherwise select2 search field in classic widgets options does not work and is shown as small empty rectangle only.

Suggestion: User proper cache buster in file paths.

Widget Options 4.0.1, WordPress 6.4.3, Classic Widgets 0.3