Problem with Default Favicons of Apps

Hi there,

I have problems with the default favicons of the apps in a current Nextcloud installation (Debian 10.3, Apache 2.4, PHP 7.3.14, MariaDB 10.3.22).
Apparently there is a problem with the conversion, because the icons look different than before.
Here is a comparison (left: Nextcloud 17.03 right: 18.01):



In the HTML source code it looks like this:

NextCloud 17.03

<link rel="icon" href="/apps/theming/favicon/calendar?v=1">
<link rel="apple-touch-icon" href="/apps/theming/icon/calendar?v=1">
<link rel="mask-icon" sizes="any" href="/apps/calendar/img/favicon-mask.svg" color="#006095">

Nextcloud 18.01

<link rel="icon" href="/index.php/apps/theming/favicon/calendar?v=0">
<link rel="apple-touch-icon" href="/index.php/apps/theming/icon/calendar?v=0">
<link rel="mask-icon" sizes="any" href="/apps/calendar/img/favicon-mask.svg" color="#0082c9">
<link rel="manifest" href="/index.php/apps/theming/manifest?v=0">

The problem also occurs with the apps.
What could be the problem here?