I do actually have a Support Request in over this. From the tl:dr: at the end of it:
"the Upload Images page should have uploaded images set to the same security as one's journal is by default, which should match the security shown on the Manage Images page, but because the upload page defaults to "public" on the dropdown, the last 3-5 images I've uploaded from DW and posted publicly, both to Support Staff and on my own DW were locked to access-only and I didn't know it, since I haven't viewed any of these pages while logged out of DW."
ETA: I closed the original Support Request and opened another after getting feedback in the comments below saying that the first request was not worded clearly enough.
All pictures I think I've set to public should now be public at this point, as I just went through my last few weeks of image uploads to make sure. My apologies to anyone who was like, "Huh" and just stopped reading because there was no image to carry the point(s) I was trying to make in whatever post(s) you came across in this condition.
Now y'all have learned I don't look at my own DW logged-out often enough to catch these things, which is maybe not the greatest fact to share with whoever runs across this, but anyhow...