I'm not sure what spec or which customers you're referring to
https://tools.ietf.org/html/rfc6177
Hence, it is strongly intended that even home sites be given multiple subnets worth of space, by default. Hence, this document still recommends giving home sites significantly more than a single /64, but does not recommend that every home site be given a /48 either.
Google and everyone else is absolutely right treating a /64 as 1 SINGLE entity.
, we offer a /112 with our VPSs to our customers.
You're not the only one doing this, I'm not singling you out, it's more of an awareness post. The confusion steps from the misunderstanding the IPv6 is a "bigger IPv4". Not really, it's a different address scheme in which the concept of "a single IP" is almost meaningless in comparison to the IPv4 IP. Considering that many hosts do it wrong, you can imagine how many end-users get it ... right.
A /64 is considered a Single End-user LAN but that doesn't mean you can't chop it up into several smaller parts and give those parts out for various usage.
You can. I've also seen hosts give 1 single IPv6 per VPS. The problem is that just because you can, doesn't mean you're doing it right. And right in this case is not about some abstract idea of correctness, no. It is a very practical thing.
For example, if your clients are sharing a /64 and only one of them has a mail server that spams, all your clients mail servers get blocked for spam. Similarly with proxies. If a single customer abuses 1 IP inside the /64, all your other customers in that subnet get blocked as well.
So, a host is punishing totally innocent clients in favor of the abuser. And for no real reason at all!
The solution is simple - give /64 per server (vps), as the rfc recommends. This will make sure your clients don't get banned because of a bad neighbor, because the big guys follow the rfc.
I didn't say that sites won't block a /64, they surely will, they just might be more reluctant when they consider the vast amounts of IPs they will be blocking, and saying that you would only have 1 proxy per /64 with IPv6 is like saying you would only have one proxy per /24 with IPv4 and this isn't the case. You can use a lot less of the /64 for proxies of course but not just one.
As you understand from above, there is absolutely no reason for "reluctance" of banning per /64. Actually there are probably "justified" in blocking per /60 or /48 in the future. But for now, /64 is the name of the game.