Page that goes down SERP despite optimizations

Hello,

I have an e-commerce site on which I have a very annoying problem for several months. Indeed, despite the many SEO optimizations made on a category page (very important because 10K searches/month), it does not manage to be placed in the first results of Google, even worse, it keeps going down in the SERP.

On this category page I have done the same SEO optimizations as on all the other pages of my site (these other pages, which all appear in the first search results), and yet, nothing is done, my category page keeps falling down.

Namely, the targeted keyword is not competitive (a new site created 3 months ago managed to place itself on the first page of Google on this same keyword ...), that I have no Google penalty, and that all my SEO signals are green. Therefore, I don't understand why my category page doesn't go up in the SERP... because, after checking, it is on average at the 50th position, which is far from being optimal...

Do you have any idea what the problem is ? Any advice on how to solve it ?

Thanks in advance, Theo