Here is the link to the official statement if you need it. https://www.ea.com/games/battlefield/battlefield-6/news/portal-101-introduction-to-battlefield-portal
"Playing Portal grants XP and Progression opportunities just like any Multiplayer mode. However, not all Portal Community Experiences grant the exact same amount of XP as Multiplayer.
When selecting a Portal Community Experience, it will either be labelled as “Verified” or “Custom” depending on what its creator chose when creating the experience.
If a Verified Portal Community Experience is chosen, then anyone who plays this experience will earn the following XP and progress at exactly the same amounts as they would in a normal Multiplayer match:
[...]"
If you can create a verified portal experience with bots, then you should get 100% progression, simple as that.
Its an oversight, not intentional, bots were added to backfill an experience not become the experience.
Thats why you can add bots to a verified game, to act as a backfill when there isn't enough players.
