How to remove onetrust icon which has appeared on Safari on iPad

A little green cookie icon called OneTrust has appeared in the bottom left corner of the Safari screen on my iPad. If I click on it it asks me for my cookie preferences. I don’t know how it got there, but it might be through a website called capitalmonitor.ai. I’ve tried deleting Safari history but it still comes back. What is it, why is it there, and how can I get rid of it please? I don’t like uninvited guests on my devices! Thanks!