Could someone explain to me why using a react app built using CRA is bad in this case? I have a similar use case where the app is on app.example.com (built using CRA) and I have a landing page (also built using CRA) on example.com

The landing page links to: - The App at app.example.com - Docs at docs.example.com - Blog at blog.example.com

I have 0 front-end experience so this is an honest attempt at understanding why I should NOT be using the CRA for a landing page.

The landing page isn't doing much so its a very simple react app. But don't understand the implications on SEO