Email Signature Update Issue

Steps to reproduce

When I try to update the email signature for users, it does not update, but the interface shows a success icon indicating it was saved correctly.

The issue is as follows: the actions are performed correctly, but when the base64 image content is saved to the database, it is too long and gets truncated.

-Steps to Reproduce

Go to the Nextcloud web interface.
Navigate to the email settings for a user.
Add or update the email signature, including an image.
Click the "Save" button.

Expected behavior

The email signature, including the image, is saved completely to the database.
The updated signature is reflected in the interface without issues.

Actual behavior

The interface shows a success icon indicating the signature has been saved correctly.
However, when the signature includes a image with a large content size, the data is truncated in the database.
As a result, the full signature does not save properly.

Mail app version

4.1.1

Nextcloud version

30.0.4

Mailserver or service

n/a

Operating system

n/a

PHP engine version

PHP 8.2

Nextcloud memory caching

n/a

Web server

Apache (supported)

Database

MySQL

Additional info

No response

Start by reproducing the issue through the Nextcloud web interface's user email settings, using an email signature with a large image. Trace how the signature is saved to the MySQL database and verify whether the complete value persists after saving. Done means the full signature, including the image, is retained and shown correctly in the interface.