"Natural immunity" is EXTREMELY suspect in this case. The vaccines are DESIGNED to target a part of the surface of the virus that is 'highly conserved'. The spike can't change much or it no longer works to allow entry into cells. So, we expect vaccine immunity to be robust.
Your body doesn't know anything about the structure of the virus. The antibodies you get from a natural infection could be sensitive to just about any part of the surface of the virus. MOST of the surface is NOT highly conserved, since it just has to act as a container for the virus. Random mutations can change the surface of the virus significantly without changing its function, but in doing so your immunity is now negated.
TL;DR - there is every reason to believe that vaccine immunity is better than natural immunity, and even if you KNOW you've had COVID, you should still get the vaccine.