You always get back whats on your side of the channel. For a 1M sat channel for example. If my side has 100k sats and the other side 900k sats. I get back 100k the other guy gets 900k. Works well

If someone got a hold of a backup of your channel and tried to restore it while you’re offline, they could try and get your sats by closing the channel. But that’s why you setup watchtowers with your peers to protect you while you’re offline. (keep in mind thats pretty unlikely)