This can also be because they bought hardware from a bad vendor, like Ubiquity, which used to support IPv6… in software routing only giving it a max throughput

This can also be because they bought hardware from a bad vendor, like Ubiquity, which used to support IPv6… in software routing only giving it a max throughput of something like 50mbps on their small business/prosumer hardware. There are also routers by brands like Microtik that have garbage IPv6 throughput unless you flash OpenWRT which packages the driver that enables hardware IPv6 routing, something that somehow wasn't included in the official firmware. All of these devices claim to support IPv6 and technically they do, so shopping for decent hardware quickly becomes a minefield. Seems to me like consumer hardware has better IPv6 support than the supposedly professional tiers.