> Kagi also uses Yandex index so it would be unusual that something exists in Yandex and not in Kagi results.

I've no reason to doubt this so I'll attribute it to which results get pushed higher in the rankings. Different entities hold power in the E & W hemispheres and that can influence search results to a degree.

Past that, there are some things I get at Yandex because Kagi seems incapable of searching for them. ex: Long strings like MD5 and larger hashes.

edit:30 seconds after posting I searched a hash and Kagi sent back a ton of results. As recently as last week I got zero results (diff hash).

That's the 2nd time in a week Kagi disproved a complaint of mine. I hope they continue to do so.