correct the solution which had previously worked no longer worked after updating to the latest stack, I found a workaround for this by changing the config.

Finally got this working with ForeignDBViaLBRepo, will stick my config here incase any is searching and hits this..

Did some additional debug, if I used the simplest form of commons:

$commonsUrl = "https://mediapool.devops.supportlabs.dell";              
$commonsName = 'mediapool';

Didn't have much time to test this today but when I set up the configuration to use the API instead I get a blank thumbnail. but the video plays (btw updated to 1.39.2)

On our own commons images and vidoes work correctly, scaling thumbnailing everything.
Also if a video is uploaded to the test wiki everything works correct scaling thumbnailing etc...

I certainly see your point there, but I keep paring the config back and really can't find an issue.

@Reedy when you attempted to reproduce this issue did you set up a separate commons wiki?
I have no issue when using instant commons.

@Reedy would you be able to share your local settings from your dev box? If so I'll try and figure out what I am doing differently to expose this.

EDIT: Corrected config and reproduced again and provided debug log. Confirmed only videos on commons wiki affected.

This looks very similar to:
https://phabricator.wikimedia.org/T272328

I have an internal alpine docker image built for mediawiki.
This issue only appears in our build after updating php to 8.1.
If I go back to php 7.4 the issue disappears.
$wgUploadDirectory is /wiki-shared/stagingwiki8/storage/images/

thanks for help, I see where I went astray now..

The minimum config I needed to reproduce this issue was:

Not in front of PC to test currently. But looking out our private gitlab I see this config:

Thanks for picking this up I’ll attempt to reproduce with a minimal LocalSettings config and post everything here.

Actually yes, pity I didn't search first.. we can close as a duplicate.. should I just close it?

Thanks @Osnard, I can confirm that patch resolves the issue we experienced, much appreciated!

Thanks for taking a look. In case it helps in root causing this, it was these comments which gave me the clue to look at groupsync:
https://www.mediawiki.org/wiki/Topic:Vn9jblaqr69fim14