Hmm I just checked, they’re all live and their status page for each link has no outages. I would check any content blockers etc. that you have, I suspect it’s a problem on your end. They do use different domains for their blog, feedback, and help KB etc.
Weird, they do, but they redirect for me and the final URL is different than what you pasted.
https://help.kagi.com/kagi/getting-started/
https://help.kagi.com/kagi/why-kagi/why-pay-for-search.html
My best guess is that a DNS record is messed up on their end, and since I’ve been to those pages before relatively recently, the cname or A-record is still cached for me.