You need to improve yoru web page performance for better user experience and SEO. Let's breakdown the rendering process to see what's going on.
Look at the iPhone Compare page, there's a whitespace inconsistency bug that's a bit annoying
Consider using Cypress when you create a new frontend project or your project doesn't have any test code before. It's simple and powerful.
I adjusted the machine types of 3 MongoDB instances, but authorization lost and no PRIMARY member error happen to my replica set...
If the user has opened multiple tabs when visiting your site, you can consider using WebSocket + SharedWorker + BroadcastChannel to broadcast your message to all opened tabs.