I've grown two Asian Pear trees from some seeds I'd collected from some fruit a couple years ago in some indoor pots, and they've been doing mostly fine (aside from a few amateur mishaps), but I need some help right now, I think. I've been trying to deal with some sunburning issues to where I've recently moved them, so I didn't notice till now that there is something getting all over one of them! There is a fine webbing sort of stuff on the underside of many of it's leaves, and there are speckles of some pale brown/tan something within the webbing. One of topmost leaves is curling in because of it. I don't see any movement of anything. Can anyone advise with what I'm dealing with here, and how to get rid of it??

Additional info: I'm in northern Alberta, Canada. The little tree is in a deep pot, indoors, has never been taken outside but there is a back door 10ish feet away from the window where the plants sit. I do not know the 'brand' of Asian Pear it is, or if the seeds grew true-to-type, as they are still too young to fruit. (These trees were planted in memory of my late dog; we both loved eating these fruits, and the seeds I collected for planting were from the fruits I still had while she was still alive.)

Photos are of (1) underside of leaf where you can see the speckles through the backlight, (2) extent of the top leaf curl, (3) best shot of the webbing I could get, (4) another leaf underside showing the speckles.