Sorry for the lack of details.
The vast majority of posts this does not occur (>95%). I simply noticed that in a few threads the occasional post by those in my community it was displaying incorrectly. When I went in to edit the post it seemed fine in preview mode, but posted incorrectly. However, If I cut the entire link text out, and then re-paste it back in. It displays how it should.
However there appears no difference in the before and after (in raw mode):
My “crawl images” is turned on.
My “create thumbnails” is turned on
Most of my settings in discourse are the default ones. Under “Files” there are a few exceptions:
" max image size kb" is set to 1000 KBs
“max image megapixels” is set to 5
“download remote images to local” is turned off.
“embed any origin” is turned on
The issue seems independent of what theme I am using. It does not happen to me, if I use the same link from a third party. What I will do is ask members of the community (who posted and had funny resizing issues) what device they were using. To try recreate the issue.