You have probably spent significant resources building tons of what you classify as “white hat” links. Next, you expect a boost in rankings and gaining massive traffic. Unfortunately, this does not come to pass; instead, you get a manual penalty in your Google Search Console. You cannot figure out what went wrong as you built only the best links you could think of.
From my experience, these are the types of backlinks you should avoid like the plague:
A sponsored post is one you have written about your business or written on your behalf, and you have paid for it to be published on another site. Ideally, it is like an advertisement. Google requires that such posts have a “nofollow” tag. If your website is audited manually, these types of backlinks will result in a manual penalty.
You can build some legitimacy by disclosing that these are sponsored posts. Google hates them because you are paying for links.
Sidebar and Footer Links
These types of links are common with web design companies and theme developers. The main problem with these links is that they result in “anchor text overoptimization.”
It is a good idea to build business profiles on various online directories. Actually, this is good for local search engine optimization. However, some directories are outright spammy. Only deal with directories that have editorial control.
N/B. The most important thing I have learned about building backlinks is that if many webmasters are using that strategy, then it is only a matter of time before everything explodes.