You might have to delete unused apps, and make it a habit to cleaan your fone memory

Go to settings -> battery and device care -> storage -> clean. You may use apps for deep cleaning invisible cache

There you'll see which apps are frequently crasing, and if you're using the client Amethyst for #nostr, maybe you need to use another client, one that won't drain your battery that much

Also, it's best to stop charging at 85% to preserve battery life, but it's best done on a new battery