Is it a topology problem?
It is helpful to upload the wire frame image.
If you are using a modifier, please mark what you use.
If you check it with a wire frame, you can see it with your eyes.
If the topology is not good, the problem is identified in the Subdivision modifier, and if the topology is somewhat problematic but does not have a significant impact, Decimate may have caused the problem.
Of course, there may be causes of problems from the underlying modeling itself.
※ The second image posted above appears to have been caused by Decimate.
The edges are clearly visible.
