mrekim did you buy this trailer new?
Last year when you repacked the bearings did you soak or clean all the existing grease from bearing?
Looking at the first picture of your post, I can see how someone might miss it, and just repack, then there is grease all over the bearing and would be hard to notice it. However part of the repacking process is to look for something like this. Don't know.
Looking at picture 2 & 3 it sure looks like someone used a flat blade screwdriver or some type of punch and drove it in with a hammer as you would have to hit the devise with something to gouge the steel like that, then pried between the race & bearing to remove or straighten/adjust the bearing and that is what bent the outer ring.
So if you bought the trailer new it must have been at the axle mfg. If bought used, then prior owner, or it could have been some kid at the dealer that knew nothing about wheel bearings and was told to check the wheel bearings.
You may never know who did it, but those gouges and the bend of the outer ring were not caused from something like a cotter pin or something in the bearing.
I don't think anything that would get into the bearing could gouge those ends in like that.