Viewer doesnt show fields for filling or signature

Steps to reproduce

1. got a pdf contract to sign via mail to nextcloud
2. opened the pdf
3. could not see any of the fields, which need to be filled (setting signature was not possible)
4. downloaded the file to desktop
5. all not shown fields wer filled
6. setting signature were possible

Example for both pdf aside eachother

Expected behaviour

Tell us what should happen

Actual behaviour

Tell us what happens instead

Server configuration

Operating system:

Web server:

Database:

PHP version:

Nextcloud version: (see Nextcloud admin page)

Where did you install Nextcloud from:

List of activated apps:

If you have access to your command line run e.g.:
sudo -u www-data php occ app:list
from within your Nextcloud installation folder

Nextcloud configuration:

If you have access to your command line run e.g.:
sudo -u www-data php occ config:list system
from within your Nextcloud installation folder

or

Insert your config.php content here
Make sure to remove all sensitive content such as passwords. (e.g. database password, passwordsalt, secret, smtp password, …)

Client configuration

Browser:

Operating system:

Logs

Nextcloud log (data/owncloud.log)

Insert your Nextcloud log here

Browser log

Insert your browser log here, this could for example include:

a) The javascript console log
b) The network log
c) ...

Start by reproducing the issue in the Nextcloud PDF viewer with a contract containing fillable and signature fields, then compare it with the downloaded file in a desktop PDF reader. No source files, tests, browser details, or server configuration are provided, so identifying the relevant viewer entry point and defining compatible field behavior requires project research.