[Bug]: CSP prevents display of custom apps in Firefox

[ne20002]

⚠️ This issue respects the following points: ⚠️

• [X] This is a bug, not a question or a configuration/webserver/proxy issue.
• [X] This issue is not already reported on Github (I've searched it).
• [X] Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• [X] Nextcloud Server is running on 64bit capable CPU, PHP and OS.
• [X] I agree to follow Nextcloud's Code of Conduct.

Bug description

With latest version of Nextcloud docker image the custom apps disappeared.

Looking in Firefox console I find this:

Steps to reproduce

1. Don't know

Expected behavior

Custom apps are available

Installation method

Official Docker image

Operating system

Debian/Ubuntu

PHP engine version

PHP 7.4

Web server

Nginx

Database engine version

PostgreSQL

Is this bug present after an update or on a fresh install?

Updated to a major version (ex. 22.2.3 to 23.0.1)

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

What user-backends are you using?

• [X] Default user-backend (database)
• [ ] LDAP/ Active Directory
• [ ] SSO - SAML
• [ ] Other

Configuration report

It affects all custom apps.
Apps work still with mobile clients.

List of activated Apps

...

Nextcloud Signing status

No errors have been found.

Nextcloud Logs

...

Additional info

No response

[ne20002]

My fault. I did forget to mount the custom apps folder in nginx.