Links that tell search engines nothing

The words of a link are how a search engine learns what the page at the other end is about. Google: "Anchor text (also known as link text) is the visible text of a link. This text tells people and Google something about the page you're linking to." A link with no words at all (an icon, or an image with an empty alt) tells it nothing; for an image link, "Google uses the alt attribute of the img element as anchor text".

Words that only say "Click here" or "Read more" are the examples Google gives of anchor text that is "too generic". Its test: "Try reading only the anchor text (out of context) and check if it's specific enough to make sense by itself." The sentence around a link still helps a reader, so generic words are a notice; a link with no words is a warning. Lighthouse checks the same thing as "Links do not have descriptive text".

Sources: Google's anchor text placement and write good anchor text; Lighthouse: link text.

Put what the page is about in the link itself:

<!-- Instead of: Our sourdough takes three days. <a href="/blog/sourdough">Read more</a> -->
<a href="/blog/sourdough">How our sourdough takes three days</a>

An image link takes its words from the image's alt:

<a href="/cakes/wedding"><img src="/img/tiers.jpg" alt="Wedding cakes"></a>

An icon link needs an aria-label, which screen readers read out too.