What causes a Storefront API internal error?

Hi

I wonder if anyone has come across this before?

A request to the storefront api to fetch a collection with filters is erroring with the not so helpful message:

Internal error. Looks like something went wrong on our end.
Request ID: {long request id here} (include this in support requests)

Shopify support aren’t being much help so have pointed me here

Any one experienced this before and know what could cause it?

Thanks

Harry