Viewing markdown files strips "data:image/...."

Nextcloud: 28.0.4
Using Text app -

I have a bunch of markdown files created locally with embeded images data:image/jpeg;base64,....

The file is synced to nextcloud and I can view the file on my linux box and the file is correct - it still has data:image.

I open the file in nextcloud (with the markdown editor) and it strips out data:image... and then saves the file - so I loose ALL my embedded images.

digging around it seems that this might be related to content-security-policy header.

Is this a bug or a setting I need to allow embeded images (data:image)?