It's a question that has been asked ever since Canon moved to mirrorless: should you use DSLR glass on your mirrorless camera, particularly when the DSLR versions are so much cheaper? A good case in point is the Canon RF 50mm f/1.8 vs Canon EF 50mm f/1.8.
During Amazon's latest sale, for example, the Canon EF 50mm f/1.8 has been slashed to just £89 in the UK. Meanwhile the mirrorless equivalent, the Canon RF 50mm f/1.8, is discounted to £165.