This is a feature called "Handoff". Use Continuity to connect your Mac, iPhone, iPad, iPod touch, and Apple Watch - Apple Support
To disable it:
- Mac: Choose Apple menu > System Preferences, then click General. Unselect “Allow Handoff between this Mac and your iCloud devices.”
- iPhone, iPad, iPod touch: Go to Settings > General > Handoff, then turn off Handoff.
- Apple Watch: In the Apple Watch app on your iPhone, tap General and turn off Enable Handoff.