How to make sure plugin is compatible with caching plugins?

If you use a caching plugin, like W3 Total Cache, Super Cache or WP Rocket, you can check the Load widget using ajax option in the view tab so the widget is loaded via ajax:

This way, you will not experience an issue for closed/open status.

Limitations

if you check this option, the countdown to closing and opening hours will not work. If you need the counter, you must uncheck this option.