Yesterday, my mom did a general cleaning on my room and when she's done, I saw the recovery phrase of my Trezor hardware wallet on the garbage can which I placed on my computer table, I also have that same copy on my wallet but still can't stop myself to tremble in fear to lose that piece of paper. I didn't told her about it to avoid more argument because she wouldn't still understand what it is.
There is no doubt that you made a mistake in leaving something so important and sensitive in such a visible place, but now I guess you have learned something from all that. If you have stored your HW safely, then treat your backup in the same way - because imagine a situation in which your HW breaks down, and then you discover that your mother threw the backup in the trash - unlike that character who is looking for his HDD in some junkyard, you wouldn't have any chance of finding an ordinary piece of paper.
This is what I've been scared about when people say to write your recovery phrases on a piece of paper instead of storing it online.
I would like to know how others keep these secret phrases if the people in your house are not really knowledgeable in crypto. Would it be safe if I store it online but the file is encrypted and password protected?
The problem is not that you use paper for backup, but in how you will store that paper. Physical storage, whether it's paper, plastic or metal, has its drawbacks, but you're sure that you won't be hacked by a hacker because you saved your backup as plain text on your computer, or you save it in the cloud or e-mail. However, everyone who has a physical backup should know that one backup is not enough, as well as that 5 backups in the same location do not make sense if that location is threatened by fire, flood, or earthquake.
You don't need to complicate things as some do, so after x years some don't know why the backup doesn't work, whether the words are mixed up or maybe there is additional protection in the form of a passphrase. Make it simple but effective.