How to return site positions?

Question

Search Engine Optimization

The site began to sag for some positions, began to dig and do not quite understand why the positions are falling. For example, the page "LED strips" https://arlight.by/catalog/svetodiodnye-lenty-100002/ . Optimization is not worse than that of competitors, but the positions sank.
I suppose that the problem is in the cannibalization of requests, because on the pages of the same section at different nesting levels there is a very similar meta, but sometimes it’s the same for competitors.
I know about multiple duplicates, this is either someone's mistake, or Bitrix failure, I'm correcting the situation. Because of this, the PS can pissimize all pages of the site, even where the unique meta is?

Answer 1

Well, you yourself answered your question with duplicates, the rest can be viewed in analytics and webmaster