Hi, @nastya.danilchenko. I see there is a support ticket about this and I replied there as well.
For the forms issue, this troubleshooting guide is the first step:
For the hydration issue, there is no server-side rendering by default at Netlify. There are workarounds for this, for example this blog post below covers using Functions to do this:
Note, that blog post is about Next.js and not about Nuxt.js. However, the general concept still applies even if the specific solution does not.
If there are other questions about this, please let us know (either here or the support ticket, whichever you prever).