3GPP 24.501 v20.0.0 — the document's own text
5.5.2.2.5 UE-initiated de-registration procedure completion for 5GS services over both 3GPP access and non-3GPP access
Taught in 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).
If the access type in the DEREGISTRATION REQUEST indicates that the de-registration procedure is for both 3GPP access and non-3GPP access when the UE is registered in the same PLMN over both accesses, the descriptions for UE-initiated de-registration procedure completion for 5GS services over 3GPP access and over non-3GPP access, as specified in clauses 5.5.2.2.3 and 5.5.2.2.4, shall be followed.