Google Ranking Factor – Anchor Text Variance
A natural link profile tends to have a distribution of anchor texts that are not always relevant to the subject matter of either the source page or the destination page. i.e. it’s not always a keyword that gets used as the anchor. That’s normal. In fact – that’s recommended.
If your link anchor texts deviate from normal behavior, your links may get more attention from the algorithm, and that can affect your rank positively or negatively, depending on how far from the norm your deviate.
Commonly used link anchors are ‘click here’ or ‘read more’ or ‘visit this site’ etc, but commercial keyword link anchors are also common, such as ‘plumbing services’ or ‘online book shop’.
The latter represent the commercially viable keyword for the destination site, and should occur at a rate that doesn’t exceed norms by too far.
Another common link anchor type is when the raw URL as the anchor, like ‘https://rankpower.co.nz’ or just ‘rankpower.net’. Depending on the nature of the domain name, URL anchors may or may not be seen as a commercial link anchor. Like for example if your domain name was classified as an Exact Match Domain.
I would expect that link anchors that use any one anchor excessively (especially commercial keywords) might be negatively affected by Penguin algorithm.