How to fix SEO? (technical question)

Hi, recently I have built my landing page with use of Next.JS, it is hosted on Vercel. I did that as I thought it might improve my SEO, however the result is much worse. My website has a lot of links marked as "Discovered - currently not indexed", only two links are working fine. The links working fine are: the root page and "/en/articles".
The website is live since the end of November, so I thought it might be already enough time for it to get crawled and indexed.
Could someone take a look and let me know what i should fix from technical point of view?
Here is my website: https://www.stonks.tech/