Operating system: MacOS Big Sur 11.2.2
Graphics card: Intel Iris Plus Graphics 1536 MB
Broken: 2.92.0 (release)
When I use substeps for Dynamic Paint it doesn't make a difference in the images generated.
Exact steps for others to reproduce the error
Add particle system to default cube
Turn the cube into a Dynamic Paint Brush, set Source to Particle System, Particle System to "ParticleSettings"
Add in a plane and scale it by 4
Turn the plane into a Dynamic Paint Canvas, set Format it to image
Set Sub-Steps to 20 (maximum)
(Optional: Set Plane cache path to something reasonable you would find later)
Click "Bake Image Sequence"
(Optional: Set Sub-Steps to 0 (minimum)
(Optional: Set Plane cache path to something different than before)
(Optional: Click "Bake Image Sequence")
(Optional: Compare baked images)
If you compare 0 Sub-Steps to 20 Sub-Steps they look the same; I think Sub-Steps has no influence on the result whatsoever.
Based on the default startup or an attached .blend file (as simple as possible).