My iPhone has been mirrored by someone

I discovered my iphone 15 is mirrored. My photos, location and music are being shared to another person with an app that disappears after its read. In addition to the carriers spyware, I've purchased malware to further prevent or curtail these activities. I dialed *#21# and discovered my call forwarding is activated. However I cant seem to deactivate it? I've read there maybe an app running in the background hidden within another app. I'm new to the apple community and the sole reason I got an iphone is for its security. I appreciate your assistance.

[Re-Titled by Moderator]