SpriteRenderer and CanvasRenderer go through two completely different rendering paths.
Here are some more potentially-useful notes about scaling / anchoring:
Usually you need to choose a suitable ScaleMode and MatchMode in the Canvas Scaler and stick with it 100%. Generally if you change those settings you will often need to redo your UI entirely.
I also use this CanvasScalerOrientationDriver utility to make sharing UI for Landscape / Portrait easier. Read what it does carefully.