There are many instances where an artist will take a fully formed song (perhaps even use the original release’s backing tracks), record original vocals/lyrics for this song and release it under a new title. The artist then avoids copyright infringement by crediting the original authors as well. The original writers get royalties for this release.
One time my sister showed me a Rihanna song. I liked it. My reaction was, “huh, I didn’t know Rihanna made cool songs.” I showed it to a friend and he said, “this is a Tame Impala song.” Unbeknownst to me, Rihanna had taken the entire Tame Impala song and simply added her own vocal/lyric. The track credited the Tame Impala writers.
I’m as big a stickler for originality as anybody. Personally, I generally feel that if someone wants to do a cover, they should just do a cover. However morally dubious I may feel the above scenario to be (exploiting the ignorance of one’s audience - the majority of listeners are not scouring the liner notes, taking account of the small-print writing credits) it is not illegal as it credits the original authors and those writers receive royalties from the release.
The Dua Lipa people could have chosen to just do a cover or at least release the song with a different title while still crediting the original writers. They chose neither. It’s simply out-and-out plagiarism.