Currently, Varnish cache is "broken" for all query parameters. This means anyone comeing from Facebook, which adds "fbclid", or from any link with standard UTM parameters like "utm_source" is served an un-cached page.

Varnish WILL then cache that entire page + query strings, but that's not very helpful.

It would be ideal to have it behave like Cloudflare APO as described here: https://developers.cloudflare.com/automatic-platform-optimization/reference/query-parameters/

So, for the "allowed" parameters, Varnish would serve cached content of the base URL without parameters.