@nottheend said:

When I check the system logs, I can see exactly at 23:00 a task, is that the beginning of the backup process?

Yes, that is the start of the full backup task.

@nottheend said:

That my backup takes almost 3 hours is fine with me. But I would like to understand what is happening before the backup is actually "created".

Depending on the backup type tgz or rsync it can take some time depending on the apps and size of the apps that need to be included in the backup.
For the integrity check everything needs to be indexed and sha256 hashed first before the backup to then validate it after the backup.
For example, Nextcloud stores image previews (thumbnails) in a hashed structured folder system within the appdata directory to optimize performance and prevent too many files in a single directory.
But this in turn leads to constant changes due to the hashed structured folder system and is so "deep" that sometimes the tgz format just fails because the folder depth, thus the name of the path, is too big to be stored in a tgz due to the primary limitation is the PATH_MAX constant, which is typically 4096 bytes.
And also takes longer time to index and hash.

@nottheend said:

The Update Schedule is set to 5 AM, and it may interfere with the Backup?

That is no issue.
When the backup takes longer, the system update task is simply scheduled after that.

Depending on the backup provider, for example SSHFS, the rsync format can be way faster than tgz.
The initial backup of rsync can take longer, but every subsequent backup is then very fast since Cloudron can do a remote-copy call instead of copying everything again and again from the Cloudron host to the provider.
This saves bandwidth and compute time, increasing the backup times significantly.
For example, my own Cloudron with 24 apps and 600 GB of backup data, only took 36 minutes 28 seconds this night to do a full backup with the rsync format on SSHFS with a Hetzner Storage Box.

@nottheend said:

I also read that before updates an Backup is taken automatically and I am not sure if that would be skipped if there is a recent backup.

A full system backup before every Cloudron update is default and is only skipped when explicitly configured so.
If you are using the rsync type backup, the backup before the update would be very fast since it just took a backup before.
Also from my system, since a backup was taken before the Cloudron update, the pre-update backup only took 4 minutes 31 seconds.

@nottheend said:

And sorry for squeezing in many questions in that post, but it may reveal some context.

All good! Always happy to help.