VPN tunnels are established successfully although traffic is dropped with "No valid SA"
That specific VPN tunnel with IKEv2 and third-party Gateway is not established in the QM phase, but a cookie of MM is written in the kernel table at every attempt. In IKEv1, a cookie of MM is deleted from the kernel tables after 2 minutes if no QM on it was established. The IKEv2 MM cookie is not deleted from the kernel tables, and the tables become full.
New VPN tunnels on IKEv1 (possibly not related to the IKEv2 tunnel) are established, but the table is full, and the MM cookie is not written to memory.