This mission concept was flawed from the start. It relies heavily on technology that doesn't exist and has no analog to build upon. Worse then that, it partners with ESA, which has it's own funding and political issues to deal with. Lastly it relies on the political will of the US Congress over a lengthily mission timeline that stretches across multiple Presidential administrations. It was always hard to see this happening and it was a clear waste of mission resources to equip Perseverance with sample collection and depository system that will likely never be retrieved. There is a better chance of people getting to Mars first and collecting the samples then a robotic sample return mission.