Migrating to Shopify mysteriously obliterated my traffic

[hypobaker]

Before Migrating to Shopify a little over 2 weeks ago, about 90% of my site traffic was organic and came through a single landing page. In order to maintain that traffic, I made a content copy of that page when moving over to Shopify. The only difference was the design and the addition of "/pages/ to the URL.

I immediately set up redirects, submitted a new sitemap to Google Search Console, and requested indexing. But bizarrely, my traffic to that page went from 300+ visitors per day, to maybe a few visitors. GSC is showing my performance plummeting, and there's no good reason for it. My pages don't have errors and the site is 10x faster than before.

And the weirdest thing is that Google has entirely removed that important page from search results containing my most relevant and previously highest ranking keywords, even though the content is identical! The few queries that Google is serving my page to are different than before, oddly specific, and less relevant.

Google is pushing me lower and lower every day and It's almost to the point where they might as well have removed my site entirely.

Does anyone have any idea what's going on here?

Thanks