Thank you all for your contribution. So if there’s no trace of those max IAS in the FCOM, I suspect this could be company specific.
However, reading an Airbus FOBN “Energy management on approach”, even if they confirm that if intercepting the GS in slats only, the plane needs 3NM/1000ft to decel to vapp, they also suggest monitoring the path and accepting ATC speeds based on a conservative 10kts/1NM deceleration rate. This means 160kts at 6NM. The maximum deceleration expressed on this document is 20kts/10nm, so also 180 to 6 as max speed appears sensible.
Looking from outside it seems a bit contradictory with their standard decelerated profile as quoted on the first post