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Canonicals will help with the trailing slash issue, but that's not the sole reason for your traffic loss. Read up on Angular and address those issues first. It's definitely going to be a boatload of work, but the impact you'll see from that will far outweigh any smaller optimizations you're able to make.

First of all, I notice 2 main errors the first one is related to the installation of the snippet code, you have repeated the local business schemas. I assume that this is generated by 2 different sources. Checking your code the error is created by the overlapping of the SEO Yoast plugin and Review plugin. The second error that I notice is the JSON-LD code generated by the review plugin which generates 22 errors "Multiple reviews should be accompanied by an aggregate rating". so basically there is no rating on the JSON-LD I strongly suggest you read this documentation https://developers.google.com/search/docs/data-types/review-snippe https://schema.org/Review Also is important to be familiar with the JSON-LD syntax https://json-ld.org/spec/latest/json-ld/ I worked on several projects integrating schemas. So in my opinion, the best way to do that is by using **Google Tag Manager+ Custom Code. Why? because that gives you full control over your schemas  **