DASH is working again
I received two helpful links from unixfox (invidious maintainer) with one regarding bypassing Youtube blocks (https://docs.invidious.io/ipv6-rotator/). This instance has now been succesfully configured to use IPv6 in Docker (and watching Youtube videos over IPv6 works now! Yay!! It didn't previously...).
The IPv6 address is changed every 12 hours to avoid a block from Youtube/Google. This instance has access to 18,446,744,073,709,551,616 IPv6 addresses (specifically /64 block). I also changed the server to a better one (it can burst now up to 2.5 Gbps).
The most important part is that, you can watch 1080p or higher videos now if you have an account on this instance! Google also doesn't get your IP address.
PS. For a little moment there was https://proxied.invidious.fi (with an unblocked IPv4 and DASH enabled), it was meant to be a temporary solution to this problem. This server will now be shut down. About 1 TiB of data flowed through it.