One of the biggest mistakes made with regards to SEO is to assume that if something is currently working well, that it will continue to do so forever.
There are several reasons for this, not least of which is Google continually changing and updating their algorithms. Entire business models have ground to a halt overnight, never to be resurrected, due to Google deciding that something which previously helped a website rank well, was in fact a negative.
One area which always seems to be in flux is backlinking or internal linking, and there are countless theories, rumours, myths, and outright misinformation as to how and where backlinks should be acquired. This creates a problem for those who have already gone out, sought backlinks legitimately, and then linked to their website.
They now might be questioning whether they should keep those backlinks or go out and look for more. The problem is exacerbated as Google continues to move from a position of simply counting the number of backlinks a website has, to a model where the power and authority of those backlinks become increasingly important ranking factors.
Google has made it clear that the so-called E-A-T measure is what they are now looking at, so Expertise, Authority and Trustworthiness is what they want to find when crawling a website. This applies not only to the website being crawled, but they are also going to take E-A-T into account when looking at what websites its backlinks are coming from.