Is the image URL the standard https://s3.amazonaws.com/appforest/… ?
There has been an ongoing issue with Windows Defender/Smart Screen marking all Bubble files (maybe all AWS S3 files, IDK) as unsafe files. Maybe your corporate email protection shares a common system?
The main issue seems to have gone away, but Bubble started a fix where the new URLs are https://[your app name].cdn.bubble.io/[uid]/filename for new uploaded files. Maybe see if a reuploaded file with that new URL makes it past your corporate email?