There’s an internal ticket for it - there’s nothing unique about which DNS provider you’re using though, it’s just that it’s not proxied and that’s only possible with Cloudflare
It’s available on Adding custom branch aliases · Cloudflare Pages docs (my own Pages project) - still needs some refactoring to be fit for merging into the producion documentation. Edit: Oh, if you mean the fact it doesn’t work with External DNS, then not that I’m aware of. The team are aware though. Edit (again): Spoken to Walshy and a ticket...