When you activate WP Rocket for the first time, some safe options will be applied by default and it can happen, after playing with other optimizations features, that you'll find your website broken.
The first thing you'll want to do is to deactivate WP Rocket but in most cases, it's not necessary. That's why, on a deactivation attempt, a modal box will propose you apply the Safe Mode:
As stated in the message, this Safe Mode will quickly disable LazyLoad, File Optimization, and CDN options. This should be enough to solve your issue in the majority of cases.
Heads up! When enabling the Safe Mode, a sub-option will export your current WP Rocket settings.
It's highly recommended to keep the box enabled to save the export file because Safe Mode will delete existent settings, and the export file will be your only way to restore them without starting from scratch. However, you can still uncheck the box and proceed.
Once the issue is solved, you can follow the basic troubleshooting method to find which option was causing the issue and find a way to fix it.
Note that you don't have to deactivate this Safe Mode, it will be automatically deactivated by enabling back the options that were turned off.