1) Blue Origin & SpaceX competing for the same NASA / DoD resources.
2) Blue Origin using government processes to block / stall contracts that would go to SpaceX.
When Musk fired a number of Seattle-based Starlink execs in mid-2018, Bezos took them in to build a competing product. After Starship launched its inaugural flight and it was clear Blue was 10-15 years behind SpaceX, the rivalry died down. By then, Bezos had already stepped down as CEO of Amazon. Now Amazon Leo / Project Kuiper exists as an inherited project.