Checking the AdSense reports (by formats), I see that my website is still showing around 200 impressions per day of 'Link Units', with the highest Impression RPM. Much higher than Vignettes'.

As far as I knew (https://support.google.com/adsense/answer/9987221), the link units were retired some years ago. Why are they being displayed on my site?

Probably, I'm still showing the code, written ad-hoc into my HTML code (honestly I do not know how to recognize that old code). If so, should I actually remove it? As commented, they are getting the highest Impression RPM.