Intentional different SPC behaviour with Agent in Group buffer?

Hi,

usually, with Emacs 30.2, when I press SPC in the Group buf-
fer, the first unread article is selected, as described in
(gnus) Selecting a Group.

However, when I press SPC on a group of a server where the
Agent is enabled and Gnus is plugged, the first unread ar-
ticle is not selected, i. e., SPC behaves like RET.

Is this intentional/documented?  If so, what is the reason-
ing?

TIA,
Tim