'Query does not contain a signature value' Error when authenticating app via proxy

I am working on a theme extension (inside of a larger app) that is installed on a dev store, and am using a tunnel set up through cloudflare. I have my proxy set up in my shopify.app.toml like so:

[app_proxy]
url = “``https://dev.elsiesandywoodstock.com/api/limits”
subpath=“limits”
prefix=“apps”

I am running shopify app dev —tunnel-url using that url above. However, when I try to hit that url in my browser, I get these errors:

10:38:21 │ React Router │ [shopify-app/INFO] Authenticating app proxy request | {shop: null}
10:38:21 │ React Router │ [shopify-app/INFO] Query does not contain a signature value. | {shop: null}

I think this is coming from the authenticate call in my api.limits route:

const { admin } = await authenticate.public.appProxy(request);

I’m not sure why this is happening. I have my api client ID and secret (copied from my app dashboard) in a .env file in my app, and I have redeployed my app since updating the toml to include the proxy. I’ve noticed in the App Proxy Url section in my admin, it’s still the old ***.myshopify.com URL that it was before, and I can’t change it to the proxy url – I thought that should have been updated with a deploy. Not sure that is even the issue but it seems wrong.

If anyone has any thoughts or pointers I would much appreciate it!! Been trying to figure this out for a few days now.