MPLS - OSPF redistributed routes appear as O IA
When OSPF is used with MPLS, the MPLS service provider backbone is considered an OSPF "superbackbone," and the Provider Edge (PE) routers act as Autonomous System Boundary Routers (ASBRs). As a result, routes originating in an OSPF area connected to a PE router of the MPLS network are considered O IA routes rather than O E1 or O E2, even if they have been redistributed from BGP.
Links:
https://forum.networklessons.com/t/mpls-layer-3-vpn-pe-ce-ospf-sham-link/1939/14?u=lagapidis
https://networklessons.com/mpls/mpls-layer-3-vpn-pe-ce-ospf-sham-link/