Worked fine until a the last few days.
I tried cleaning it, but it doesn't help.
The robot itself and the brushes move: everything else seems fine.
Therefore it seems that something connected to the sucking motor has broken.
A vacuum that doesn't vacuum is useless.
It also seems to be a common Problem:
https://www.reddit.com/r/Dreame_Tech/comments/1aurs53/dreame_l10s_ultra_stopped_vaccumingsucking/
https://www.reddit.com/r/Dreame_Tech/comments/zy6tfo/l10s_ultra_not_vacuuming/