Apparently it is something to do with glib2, which the devs are aware of and will tackle.
Rather than downgrading (= risky) I will run Ts via the terminal.
That is the conclusion I have come to.
So, for other users who encounter this problem, the steps to take are:
- if you have installed Timeshift, uninstall and install
yay -S timeshift-bin - set the Settings as per your preferences
- enable a running cron:
sudo systemctl enable --now cronie
Timeshift should not start creating snapshots as per your settings. You might need a restart of Endeavour.
If the automatic snapshots still are not done, create them by running Timeshift via the terminal: timeshift --create. To see all the options possible: timeshift --help.