Custom Safari extensions disappear

The new iOS 27 feature for describing a Safari extension really excited me. I actually created a useful extension that worked exactly how I wanted it to on the third try. My problem is that it only seems to exist for a day, and then it vanishes from the page menu.
When first described, it appears as a button in the top left corner of the page. It took me a while to figure out that I had to pick a color and icon for the extension before it really existed. That's a little annoying and a confusing interface besides. Still, I did get it to be a feature I could run or not run on any page for a short period of time.
My Safari extension has now vanished for the third time. My official Safari extensions from the store have not vanished.
Has anyone else had this problem?
Does anyone know a solution?
I am trying this on iOS 27.0.1 on an iPhone 18 Pro.