Search for file "th-product-review.liquid" in Admin code. when you open this file you will see CSS & JS file, Whenever you update CSS or JS file at that moment you need to pass a random number as a parameter as shown in after changes image.
For example:
{{ '//thimatic-apps.com/product_review/theme_files/wc-review.css?v=1' | stylesheet_tag }}
{{ '//thimatic-apps.com/product_review/theme_files/wc-product-review.js?v=9898' | script_tag }}
Default Code before changes:
Code after changes:
Note: Whenever single change made in these CSS or JS file then must change the value of passed parameter.