I used the checker for my banner, and he shows me some new banner , I didn't added to my profile,
on the other hand , some of my banner , already added where not found in the caches I had logged .
So a good tool , but not 100%
There is an other Beta tool, which will go through a gpx file (so you have to create at first a gpx file of all your logged caches) and will try to discover the banner info and will create a list of the banners.
Also it will create the coding needed to be added to your profile to show the banners.
here is the link: https://baronbale.de/de/tools/gc/banner/
It is german, but translated with deepl https://www.deepl.com/translator
you will get it
give it a try