Ncp.cfg - usage and content

Nextcloud version : 25.0.3.2
Operating system and version : raspbian bullseye
Apache or nginx version : Apache 2.4.56
PHP version : 8.1.20

The issue you are facing:
I am trying to find out why ncp-upgrade-nc is rolling back php from 8.1 to 7.4 when trying to do an upgrade to 25.0.6.
I found that this is the content of ncp.cfg:

{
“nextcloud_version”: “26.0.1”,
“php_version”: “7.4”,
“release”: “bullseye”
}

Can the difference in php and nc versions be the reason for ncp-update-nc?
… or more general, what is ncp.cfg for?

Thank you,
kr,
Martin

Mine looks like this:
cat /usr/local/etc/ncp.cfg
{
“nextcloud_version”: “26.0.1”,
“php_version”: “8.1”,
“release”: “bullseye”
}