I would say if you're less than happy with your Dyson (separate from the Roomba issues) look in to some alternatives. They are the jack of all trades and master of none.

With your Roomba if you've been diligent about going behind it and the clumps are still occurring then you should look in to a different model/brand.

Roomba relies on the dual brushroller design in their cheaper models to make up for their lower than the competition suction. The i7 and i9 have higher suction which makes them perform a lot better when it comes to pet hair and hard floors.

Vacuum Wars also went over most of the robotic options for 2020. Unfortunately he doesn't have the same experience with the low end Roombas when it comes to hair, but some of the specs he provides can show how the low suction could be limiting the ability of your vacuum to actually pick up undercoat fur from your rug.