That said I have just visited your link without issue, see attached screenshot.
If you are still getting this alert, please attach a screenshot of the Avast Alert window (with the more details option open). See screenshot 2 on how to attach.
Unfortunately that old History entry screenshot doesn’t provide a great deal of information.
If you can replicate it and post a screenshot of the Avast Alert window (with the more details option open) it may provide more information. It is strange that you don’t get this when you first open it (as I also found).
As I said you can report it, but the virus labs team are likely to see the same as you and I on first opening the site.