Some sites hosted on InfinityFree seemed to be indexed fine by Yandex, but others do not. The reason isn’t really known with absolute certainty.
Not intentionally as far as I’m aware of, especially since you are able to sign up for the services and host a website here just fine. As mentioned in the thread I linked you to, Yandex keeps changing their IP ranges, so keeping track of the changes and constantly updating the whitelist to prevent the security system from blocking their requests isn’t an easy task.
Use a different search engine? Most of them shouldn’t have an issue.
Perhaps you can utilize Cloudflare and see if Yandex is able to index the page then. We have a guide for that, if you want to try it out: