Hi, I experienced this exact same problem and never found a solution for it.
Every time I add another container to my macvlan or reboot one of the existing, my router receives another DHCP lease with a random MAC address and the the hostname of my docker host.
This makes my docker host unreachable by its name, since DNS now has several entries for all these random MAC addresses.
I found out, that it seems to be Raspberry Pi related. Tested this on a Pi 2 und Pi 4 with different kernels (4.19.118 to 5.4.83) of Raspbian / RaspiOS and HypriotOS aswell. Allways the same behaviour.
But when I run the same configuration on a PC hardware with Debian 4.19.118 as a docker host, this issue does NOT occur.
Any ideas for further troubleshooting are appreciated 
@dreiekk did you ever solve this issue or found a workaround?
Thanks!
Kind regards
Thomas