WIndows 10 host always requests DHCPv6 address

My Windows 10 PC is connected to a dual stack (IPv4 IPv6) network. After checking the Router Advertisements of this network, I saw that no RA flag is set in its router advertisements, although there is a DHCPv6 service running on that network. Based on the configuration above, I would expect that hosts would not request an DHCPv6 address, since the M-flag is not set. This expected behaviour is verified on a raspberry-pi device connected to the same network, which gets no IPv6 (SLAAC is also disabled on this network). However, my Windows 10 PC seems to ignore the RA flags and requests a DHCPv6

Question by NickG on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.