Is there any way for me to re-gain my data via sync feature?

All of these have username/password combinations and there have been many accounts hacked over the years. Even one of my Google accounts had been compromised in the past. Brave avoids this by never having us create username/password combinations and using secure methods.

It’s also important to note Brave doesn’t have Sync to be used as a backup or anything. It is only for you to actively share data between devices you are using. This is why the sync phrase changes daily. If you want to keep things secured, you should be exporting data and/or doing regular backups to an external drive or something.

Big thing to remember is privacy vs security vs convenience. Places like Google are collecting and selling your data. Unlike the others you listed, Brave has primary focus on privacy and security. Sometimes this means conveniences like accounts you mentioned will take a backseat.

Read through Sync is not a backup