IPv6 is pointless and still a security risk but I’m guessing you’re misconfiguring something.
Assigning only /64 & no DHCP-PD. There's not much to misconfigure, since in IPv6 you have to use their router and they are pushing the config.
And since you have only /64, you cannot put another router behind theirs.
> The following sections explain why /48 and /56 are the recommended prefix assignment sizes for end customers.
* https://www.ripe.net/publications/docs/ripe-690/#4-2--prefix...
And it's not like it's a new policy:
> RIPE-690 outlines best current operational practices for the assignment of IPv6 prefixes (i.e. a block of IPv6 addresses) for end-users, as making wrong choices when designing an IPv6 network will eventually have negative implications for deployment and require further effort such as renumbering when the network is already in operation. In particular, assigning IPv6 prefixes longer than /56 to residential customers is strongly discouraged, with /48 recommended for business customers. This will allow plenty of space for future expansion and sub-netting without the need for renumbering, whilst persistent prefixes (i.e. static) should be highly preferred for simplicity, stability and cost reasons.
* https://www.internetsociety.org/blog/2017/10/ipv6-prefix-ass...
The other big one I know, Jio (from Reliance) also offers just a single /64.
Where I'm, I can choose 1 out of 1 broadband provider available in the area. With this provider, I can either have a public IPv4 address (or several) with their CPE in bridge mode, or DS-Lite, with IPv4 CGNAT without PCP and /64 for the IPv6 addresses (i.e. no address space for subnets, no prefix distribution) AND having to use their router with the limited settings they allow.
With offers like these, is it any wonder that I stick with IPv4?