doc/dirmngr.texi:
"These are the same as the global @option{--keyserver-options}
from below, but apply only to this particular keyserver."
However, there are no other mention of keyserver-options in that document.
This is related to T2147.
Apparently as a new user I cannot comment on bugs. Please grant me permission to
do that (although I do not need it at the moment).