Hello, I was investigating Google Search Console crawl errors and am observing unexpected behavior of the 404page plugin. I deactivated all but the following plugins:
1. Really Simple SSL
2. Under Construction
3. Wordfence Security
4. 404page – your smart custom 404 error page

Theme is Twenty Twenty.

I’m observing that when I enable the plugin Media Library Assistant and
1.
Attempt to access an attachment tag page that doesn’t exist, for example: https://fedhillphoto.com/attachment_tag/foo, I observe an unexpected error page, see this screenshot: https://fedhillphoto.com/wp-content/uploads/observed404.jpg.
2.
When I access a non-attachment page that doesn’t exist, for example: https://fedhillphoto.com/foo redrects to the expected error page I created with 404page, see this screenshot: https://fedhillphoto.com/wp-content/uploads/expected404.jpg.

Could you please investigate?

Please note I’ve had to re-enable everything so my site is functional enough for visitors.