It should be noted that the decision was made to require a login to view or post images on the site. This was to make it so that the service did not attract unwanted users. It may be that the algorithm used by Gen Digital products is triggered (falsely) by this requirement.
Ah, you may be on to something! An issue that I have long meant to raise but never got around to it, is how thumbnail and medium images are linked to the full size version.
e.g. This is the BBCode TM-IMG generates for a medium linked image:
[url=https://tm-img.com/image/ViT34][img]https://tm-img.com/images/2024/07/14/20240714_141838.md.jpg[/img][/url]
This results in a medium size image embedded in the post which if you click on will take you the
page for the full-size image on tm-img.com. The problem with this is that you need to login to view the image. I always get around this by substituting the URL for the full image in place of the page URL in the link.
Perhaps the AV products have now decided that all links to a login page within an image are phishing attempts?
I notice that the behaviour is different on other hosting sites. imgbb.com links in the same way but doesn't require a login to view the full image page.