git bisect is pointing to commit 12588d2 (Fix height)

DynamicEnvironmentMapManager.js, line 246:

  position: {
    get: function () {
      return this._position;
    },
    set: function (value) {
      if (
        Cartesian3.equalsEpsilon(
          value,
          this._position,
          0.0,
          this.maximumPositionEpsilon,
        )
      ) {
        return;
      }

      this._position = Cartesian3.clone(value, this._position);
      this.reset();
    },
  },

The setter was updated with an absolute and relative epsilon, which causes this regression.
Not sure however how this can be explained...

So yes, this is clear now: if the entity moves for more than 1000m (default DynamicEnvironmentMapManager.maximumPositionEpsilon value), then a new environment map is created. This clearly tears performances down.

So is there a way to disable this ?

I don't see any easy way to workaround this regression right now!
What would be the best way to fix it, still using the entity framework?
My first though would be to add another option to ModelGraphics constructor and to propagate it down to ModelVizualizer, and then use it to configure or disable the model's DynamicEnvironmentMapManager if it's possible.

What are your thoughts?

Thanks for pointing this out @jfayot! I'm looking into https://community.cesium.com/t/procedural-ibl-gpu-memory-leak/36760 now to hopefully address the underlying issue.

My first though would be to add another option to ModelGraphics constructor and to propagate it down to ModelVizualizer, and then use it to configure or disable the model's DynamicEnvironmentMapManager if it's possible.

I think this general approach will work, but have a more specific suggestion that I will comment over in your PR: #12358.