Information
By default, IKEv2 uses Diffie-Hellman group 16 in the IKE key exchange. This group uses the 4096-bit more modular exponential (MODP) group during IKE key exchange.
See https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/security/vedge-20-x/security-book/config-sec-param.html for more information.
Solution
You can change the group number to 2 (for 1024-bit MODP), 14 (2048-bit MODP), or 15 (3072-bit MODP):
vEdge(config)# vpn vpn-id interface ipsecnumber ike
vEdge(config-ike)# group number