Possible consequences of link hiding for a specific user-agent?

Question

Google

In general, there is such an idea. For some pages of the site, add the rel="nofollow" tag to the links, but do it so that visitors do not see it, but for example, Yandex and Google see it. Do it with php.
The question is, has anyone done something like this and what can happen to the site if the search robot notices this?

Answer 1

It's called cloaking. Do it, but not on the main site.