PDF Thumbnails shown as independent pictures in "Photos" view

[liquidsunshine]

Describe the bug
After using the Preview Generator to pre-generate thumbnails across my files, the thumbnails for the PDFs (but not the PDFs themselves) are showing up under the "Photos" app/tab. They have filenames like !2019_04_06_14_08_50~pdf!00001N_001.jpg.

This occurs in the web interface but not the iOS app. The iOS app seems to properly filter out these thumbnails, even with the "media" folder set to the file root.

To Reproduce
Steps to reproduce the behavior:

1. Add some PDF documents
2. Install the Preview Generator app and generate previews with the occ command
3. Go to the Photos app
4. See thumbnails of the PDFs show up mixed within actual pictures

Expected behavior
These thumbnails should not show up in the Photos app/tab.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: Ubuntu 22.04
• Browser: Firefox
• Version: 122.0 (latest)

Smartphone (please complete the following information):

• Device: iPhone 13 Pro
• OS: iOS 17.3
• App: Nextcloud iOS App
• Version: 4.9.6 (latest)

Browser log

JQMIGRATE: Migrate is installed, version 3.4.1 [jquery-migrate.min.js:2:980](webpack:///nextcloud/node_modules/jquery-migrate/dist/jquery-migrate.min.js)
Global search initialized! [GlobalSearch.vue:51](webpack:///nextcloud/core/src/views/GlobalSearch.vue)
OCA.Files.Sidebar initialized [Sidebar.js:36:10](webpack:///nextcloud/apps/files/src/services/Sidebar.js)
OCA.Comments.View initialized [comments-app.js:32:8](webpack:///nextcloud/apps/comments/src/comments-app.js)
OCA.Sharing.ShareSearch initialized [ShareSearch.js:33:10](webpack:///nextcloud/apps/files_sharing/src/services/ShareSearch.js)
OCA.Sharing.ExternalLinkActions initialized [ExternalLinkActions.js:33:10](webpack:///nextcloud/apps/files_sharing/src/services/ExternalLinkActions.js)
OCA.Sharing.ExternalShareActions initialized [ExternalShareActions.js:33:10](webpack:///nextcloud/apps/files_sharing/src/services/ExternalShareActions.js)
[WARN] viewer: Some mimes were ignored because they are not enabled in the server previews config 
Object { app: "viewer", uid: "donni", level: 2, ignoredMimes: (1) […] }
[ConsoleLogger.js:71:18](webpack:///viewer/node_modules/@nextcloud/logger/dist/ConsoleLogger.js)
OCA.Viewer initialized [Viewer.js:81:10](webpack:///viewer/src/services/Viewer.js)
session heartbeat polling started [session-heartbeat.js:103:9](webpack:///nextcloud/core/src/session-heartbeat.js)
Proxying an event bus of version 3.1.0 with 1.3.0 [index.es.js:2337:14](webpack:///notifications/node_modules/@nextcloud/notify_push/node_modules/@nextcloud/auth/node_modules/@nextcloud/event-bus/dist/index.es.js)
Registering notifications container as a menu [NotificationsApp.vue:219](webpack:///notifications/src/NotificationsApp.vue)
Notifications permissions granted [NotificationsApp.vue:453](webpack:///notifications/src/NotificationsApp.vue)
Polling interval updated to 30000 [NotificationsApp.vue:416](webpack:///notifications/src/NotificationsApp.vue)
Started background fetcher as session_keepalive is enabled [NotificationsApp.vue:275](webpack:///notifications/src/NotificationsApp.vue)
Contacts 
Array []
[GlobalSearchModal.vue:247](webpack:///nextcloud/core/src/views/GlobalSearchModal.vue)
Search providers 
Array(6) [ {…}, {…}, {…}, {…}, {…}, {…} ]
[GlobalSearchModal.vue:243](webpack:///nextcloud/core/src/views/GlobalSearchModal.vue)
Got notification data, restoring default polling interval. [NotificationsApp.vue:376](webpack:///notifications/src/NotificationsApp.vue)

Additional context
Add any other context about the problem here.