If it has any interest, here is some additional info.

Another way to produce the same error is to make a particle system, and under Shape:
Shape: Box
Emit From: Shell
Texture: any texture

Save and restart Unity, then click node with particle system and it will spam these two errors:

GUI Error: You are pushing more GUIClips than you are popping. Make sure they are balanced.
UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&)

NullReferenceException: Object reference not set to an instance of an object
UnityEditor.ShapeModuleUI.OnSceneViewTextureGUI (UnityEngine.ParticleSystem+ShapeModule shapeModule, UnityEngine.Mesh mesh, System.Boolean twoSided, UnityEngine.Material mat, UnityEngine.Matrix4x4 transform) (at <f410fc5435e441ef807a07ba817c3e30>:0)
UnityEditor.ShapeModuleUI.OnShapeToolGUI (System.Boolean allowGizmoEditing, System.Collections.Generic.IEnumerable`1[T] targets) (at <f410fc5435e441ef807a07ba817c3e30>:0)
UnityEditor.ShapeModuleUI+ShapeGizmoTool.OnDrawHandles () (at <f410fc5435e441ef807a07ba817c3e30>:0)
UnityEditor.EditorTools.EditorToolManager.InvokeOnSceneGUICustomEditorTools () (at <f410fc5435e441ef807a07ba817c3e30>:0)
UnityEditor.SceneView.CallOnSceneGUI () (at <f410fc5435e441ef807a07ba817c3e30>:0)
UnityEditor.SceneView.HandleSelectionAndOnSceneGUI () (at <f410fc5435e441ef807a07ba817c3e30>:0)
UnityEditor.SceneView.DoOnGUI () (at <f410fc5435e441ef807a07ba817c3e30>:0)
UnityEditor.SceneView.OnSceneGUI () (at <f410fc5435e441ef807a07ba817c3e30>:0)
UnityEngine.UIElements.IMGUIContainer.DoOnGUI (UnityEngine.Event evt, UnityEngine.Matrix4x4 parentTransform, UnityEngine.Rect clippingRect, System.Boolean isComputingLayout, UnityEngine.Rect layoutSize, System.Action onGUIHandler, System.Boolean canAffectFocus) (at <8c4c0c3614e7457984f7ec0d5dc10278>:0)
UnityEngine.UIElements.IMGUIContainer.HandleIMGUIEvent (UnityEngine.Event e, UnityEngine.Matrix4x4 worldTransform, UnityEngine.Rect clippingRect, System.Action onGUIHandler, System.Boolean canAffectFocus) (at <8c4c0c3614e7457984f7ec0d5dc10278>:0)
UnityEngine.UIElements.IMGUIContainer.DoIMGUIRepaint () (at <8c4c0c3614e7457984f7ec0d5dc10278>:0)
UnityEngine.UIElements.UIR.RenderChainCommand.ExecuteNonDrawMesh (UnityEngine.UIElements.UIR.DrawParams drawParams, System.Single pixelsPerPoint, System.Exception& immediateException) (at <8c4c0c3614e7457984f7ec0d5dc10278>:0)
Rethrow as ImmediateModeException
UnityEngine.UIElements.UIR.RenderChain.Render () (at <8c4c0c3614e7457984f7ec0d5dc10278>:0)

As soon as You click on "Shape" again, the gizmo will appear correctly and the error spam will stop; then You will not see the error again until You restart Unity and click the particle system node once again.

If You set texture: none the error will also stop, so I would say that is the trigger (in my case).

Since it seem to be a problem with the Gizmo, I would assume it wont affect runtime or builds.
Produced with Unity 2022.2.0b4.2768.