Sudden drop in Impressions

Hi guys!

I have a recent shop which was getting more daily impressions as the site was getting more mature and more backlinks were being indexed.

Since one week I have a sudden and consistent drop in impressions which I don’t really understand. I get that it can’t be increasing forever but a drop now that most of backlinks are still being indexed I don’t understand.

I also have the issue that most of the pages are not indexed (for valid reasons like having the proper canonical version) but my question is, does the Not Indexed / Indexed ration affect the page performance and therefore the number of impressions?

Thanks for your help!