100-address trap? I'm not aware of such things, is it an exploit of some sorts? Private key extraction through social engineering?
It's not an exploit. It means that backups are only good for 100 transactions from the time of backup. After that bitcoin core generates new private keys that are not in the backup you made so you must make a fresh backup. If you fail to do that and the wallet file on your hard drive is corrupted you lose money.
Thank you.