It's easy to make an account yourself.

It's certainly a possibility, so thanks for pointing that out, though with those blocks, you'll typically get a 'blocked' page explaining all that for you, or perhaps a certificate error, which if you decide to ignore, will lead you to the blocked page. The only other possibility is that the page doesn't load at all - the browser will claim the connection failed.

If you get any other error, e.g. a 429 response code, it's not being blocked by your ISP. I've seen such errors from Nyaa enough times myself to presume their own IP blocking would play quite a role.