I had the /64 via DHCPv6-PD/SLAAC.

The /128 is given to any clients that connect as there is no NAT and the ISP isn't worried if I use a thousand addresses.

A /128 is a single address and given the state of v6 NAT that means it can’t be shared with other machines in your network which means only your router will be able to access the v6 internet without the router being a proxy and you using it

No it means my router is not routing IPv6 traffic. It doesn't need to though. My router and all of my computers each have /128 addresses. No issues. 19/20 on ipv6-test.com.

I got a /48, and I think it will take me a while to put all those addresses in use. I'm using 9-10 now, so while I've certainly started down the path, the end is not in sight just yet.

You need a /48 (or /56) if you want to do your own subnetting and keep using SLAAC (which is the default way for assigning v6 addresses and detecting address conflicts).

A /64 is not enough for that. You can still create your own subnets, but you will be on your own with address assignment

Name and shame the ISP that won't let you do a prefix delegation request to get a larger prefix assigned...

BellAliant in eastern Canada, the only provider of residential layer 1 fiber in my area, still isn't even assigning a /128 or /64, let alone proper delegation.

That's an ISP that apparently still doesn't offer IPv6 at all... not an ISP that has a misconfigured IPv6 network.

Not offering IPv6 is intentional misconfiguration in this day and age, and deserves shame.