When switching tabs / different open images, the image you switched to briefly shows with a "Zoom to Fit" zoom level, before then going to the zoom level you had actually set when you last worked in that tab.
See attached video, where I have various images that I have set to 100% zoom. Switching between them briefly shows them blown up to fit, before then showing them at 100%. (just noticed that the flash of zoom to fit doesn't appear for some in the video...I suspect the flash fell between framerate of the video, but doing it live it does it for ALL tab switches)
Not a major bug, but more of an annoyance.
affinity-photo-100percent-switch.mp4