The thing is, this kind of license is only really relevant to the kinds of projects that do have legal teams.
If you're writing a hobby project you probably shouldn't waste time worrying about feeding the AWS machine, because the odds that you'll get noticed and used are tiny. Just pick GPL or MIT and be done with it.
If you're participating in a large decentralized project like Postgres, then having a big player like Amazon providing managed hosting is actually a huge plus because you get lots of contributions from the big players [0]. There's very little downside for a project like this, and lots of upside.
The only type of FOSS project that needs an "AWS can't use this" license is a project that is driven by a single for-profit company which decided to make their business model "provide a managed solution layered on top of AWS". Unsurprisingly, it's hard to compete with AWS on price when you're using AWS itself as your vendor, so these companies tend to be the ones that switch licenses to tell AWS they're not allowed to compete.
These companies almost certainly have their own legal counsel and they represent a tiny minority of FOSS projects, so it's not obvious to me that we need a new standardized anti-AWS license. Maybe we should instead acknowledge that "managed-hosting-supported FOSS database" is an impossible business model and try something different next time.