Replicating this bug is pretty simple, zoom in/out on a regular note and it affects the zoom level inside canvas cards. The zoom level of canvas cards gets affected even when you don’t have a canvas file open if you zoom on a regular note.
At least for me this bug is bothersome, because I try to align the text in my canvas cards precisely for easier reading and a more organized look. It’s frustrating to open a canvas file to see that everything has gotten unaligned because I had zoomed on an unrelated note.
Here are some example screenshots, note that I only zoomed on the note on the left, but the canvas on the right was still affected: