Why did I create a new website and not update the old one?
The main problem was I wasn't too familiar with C# and UmbracoCMS to develop rapidly. It took ages to implement new features and they didn't work as well because I'm not as experienced as I would like to be. It works wonderfully well if you’re a really experienced programmer, but at the moment I can't teach myself all languages at the same time. Therefore, I decided to go back to NextJS or to Astro. Because I'm already a bit familiar NextJS I chose that one. Server Side Rendering and Client Rendering can be a pain in the ass but after sometime you'll become comfortable with it.
Hurdles
A bit of a hurdle was to implement a hit and a like counter. You can view the hits of every page from a unique viewer, and you can also like a single page up to 10x times. I implemented this with a NextJS API and Redis database/storage and at the beginning it worked well, but after some time I got some problems that I still had to investigate further. With no prior experience in redis it was a kind of 'big' step to teach myself something new. But I'll get it to work, and you will see the output all over the website.
Performance
Thus, this website is built with React and NextJS (SSR) the performance of this website should also be a lot better than the old one. I'm not sure at the moment if I host the website on Vercel or on my private server, but I think I'll go with vercel.
Editing with MDX
I saw a post from Josh Comeau how he built his wonderful beautiful website and then decided to build the 'same' one with kind of the same technologies only different from the looks. With MDX I'm not very familiar at the moment, but that will come after some time I guess. It makes writing text a lot faster and less annoying because of it's simplicity.