Pop and rock are both wide genres so this is a bit broad but:

Lissie and Phoebe Bridgers have also covered Nothing Else Matters Lissie: https://youtu.be/0Ia9N9MdSa0

Phoebe: https://youtu.be/I1qRuz9D7OQ

Phoebe Bridgers has also covered Wheatus' Teenage Dirtbag: https://youtu.be/t3BmrWXYif0

Lana Del Rey covered Sublime's Doin Time https://youtu.be/b6UazdAlqhs

Holly Humberstone covered Radiohead's Fake Plastic Trees https://youtu.be/uEDERBIdNxw

Halsey covered Death Cab for Cutie's I Will Follow You into the Dark https://youtu.be/ZAYBCJGk07s

Lorde covered Phil Collin's In the Air Tonight https://youtu.be/_bhvufnPkxc

Florence + The Machine covered Fleetwood Mac's The Chain https://youtu.be/kF-hMABAr74