If you are a cited expert on a topic and the website lists you as an expert, and you are connecting to a page on your website that gives a value-added explanation of a concept, then a do follow link makes sense.

Here are a couple such examples:

You are discussing a topic that has a formula or requires an in-depth explanation.

However, such an explanation adds nothing to the article. You may provide a backlink to yourself to let the reader understand more. The same is true for your author biography.

If you're a regular contributor and people subscribe to your column, it is sensible to provide a link to your website so that your admirers may interact with you. This also contributes to the 'E-A-T' notion if your website includes other publications, awards, and certifications.

If you paid to post, there needs to be an advertising disclaimer that payment (cash, product for review, etc.) was exchanged.

Google will soon get more adept at searching for this.

When Google does this, I expect them to try to link the 'dofollow' link to your site to the disclaimer, and the link may not count as much (if at all) because it is plainly sponsored or put by you as the author.

Why not simply remove the disclaimer?

If there is no disclaimer or disclosure, you may be in violation of the FTC (here's a nice guide they produced) and several foreign guidelines. I'm not a lawyer, so I can't say for certain, but you should be informed. I assume the same restrictions apply to you in the United Kingdom.

If the blog you're guest posting on is part of a PBN (private blogger network), and the PBN has been mapped or is known to Google, and you utilize the same type of guest posting as a link acquisition method, you may be punished.

Many people who use guest writing for backlinks try to mask or disguise their backlinks by linking to competitors and other credible resources, but this isn't perfect and can still be detected. You're in a pretty ambiguous situation. To be safe, request sponsored or nofollow markup and only post to sites that will bring a relevant audience to your own page.

Guest writing for backlinks is not a viable tactic in and of itself.

A smart technique is to provide truly good material that solves a problem or simplifies understanding of a topic. Next, contact the blog owner through email (do not use a template) and let them know you enjoyed their site, using particular callouts to demonstrate you read it. Finally, emphasize that their website does not provide a solution for AB.

This is when you come into play. You may now either send a link and indicate it may be of interest to their readers, or you can ask if it is okay to have them review it or provide input.

I have a better response rate when I seek permission first because I approach the blogger in a more polite and engaging manner. However, you must personalize the email and make it about them, not about you. I hope this helps, and thanks for your query! This is a frequently discussed subject.