Google Maps has one, even. And Stripe.
I like that. Easy to tell if you should keep the key a secret or not.
(Although `pk` always freaks me out. Public or private?! Oh, right, the other one's "secret".)
The only purpose of the keys Maps/Stripe encourage you to publicly put into your website is to guarantee it is talking to _your_ Google/Stripe account not someone else's. Obviously once you put them in your client they are of zero value in helping Google/Stripe identify you. The fact that Google allows you to use the same type of key they also use elsewhere to identify _you_ not _them_ was always incredibly bad design. Google already have the 'Project ID' which would have been the best thing to use.
But the fact that permissions are not hardened at time of creation is bonkers to me.