Another option that you see at the port level is Tag Stacking. This option can be enabled or disabled. If you enable it, then in case a frame comes to the ingress of the port with a VLAN ID different than the VLAN ID which is set on that port, then  it will add another VLAN tag with the PVID value on top of any other tag for all ingress packets. How to set it? It is very easy; you just need to check the Tag Stacking inside the port itself as you can see here: