You might be taking voice lessons every week or even multiple times a week. Perhaps your practicing execution of pitches and runs. Maybe you're performing at church or in open mics.
All of this is great, but are you singing harmonies? Are you singing with other people? This is one of the most joyful parts of singing. A magical feeling of syncing with someone else's frequency in their body (LITERALLY.)
There are lots of options for learning harmonies. Here are some things you could try:
Join a church or community choir. Usually free and you least intimidating. The music in some cases is a little cringe but it'll teach you in a nurturing setting.
Take a Singing Workshop. (Try my Singing for Fun Vocal Workshop). This is awesome especially because often choirs/choruses have a totally different repertoire. In a small workshop you're more likely to sing contemporary harmonies- maybe a Billie Eilish song or Harry styles :-)
Listen to recordings and randomly sing a note that's not the melody. See if it fits. Maybe try a little lower or higher if it feels off.