To be honest, I don't know if this is advertising. This is because around two weeks ago, someone posted a study with puzzles in it and around three weeks ago, someone posted a study about the London System (i think). When I claimed that the study with puzzles was advertising, thibault (i'm not joking), disliked my post, so I deleted my post. In the study about the London System, I was faced with controversy.
Topic about London system here:
lichess.org/forum/general-chess-discussion/i-made-a-study-of-the-london-system#5I couldn't find the puzzle study topic.