Operating system: Windows 10 (Latest)
Graphics card: NVIDIA GeForce GTX 1060
2.80 Beta, 2019-01-23 00:32, dc3b5024be1a, Branch: blender2.7ender2.7
Short description of error
Loose polygons appear on the mesh while working with "Dyntopo" with "Relative Detail" in "Sculpt Mode". They go away if you toggle "Sculpt Mode".
Exact steps for others to reproduce the error
Use default cube. Go into "Sculpt Mode". Enable "Dyntopo" with "Relative Detail". Issue is better observed on the thin parts of the mesh, which can be made with "Snake Hook" brush. Zoom in closer to the surface, do some strokes, get high detail. Zoom away, do some strokes in the same place, this will reduce detail now. While repeating these steps, if overall shape of surface changes, it leaves behind loose polygons, which will disappear when you go to "Object Mode" and back into "Sculpt Mode".