Hi there! Specifically with iframes when using "mobile full-page" template, hotspot popup images now scale based on the viewer Width that you specify on the Interface tab in SpotEditor.
So in your SpotEditor project under Interface tab, set the Width parameter to the desired width of the view when its viewed on a desktop monitor (i.e fully expanded). This will be the viewer width at which your popup image will show at its Max Width as configured on the Hotspot form on the Image Content tab.
We then use the "base" viewer width as the basis for scaling the popup image, i.e the popup images will resize relative to the change of the viewer width, e.g on a mobile screen.
This was one of the additions in v3.6.5 beta build 116 (released on 08-January-2021). See version history here:https://www.webrotate360.com/products/w ... story.aspx
PS: we plan to expand on this and add more sizing controls for popup images such as "minimum width" in the upcoming v3.6.5 updates.