Existence of semantically justified set axioms beyond ZF
Ascertain whether there exist set-theoretic axioms beyond the Zermelo–Fraenkel axioms that admit semantic justification grounded in an objective conception of the set-theoretic universe, and identify such axioms if they exist.
References
It is not clear whether, besides the ZF axioms, there are other set-theoretic axioms with semantic justification (see [1]).
— Kurt Gödel and the Logic of Concepts
(2406.05442 - Kostić et al., 8 Jun 2024) in Section 3.2.1