#4 R-Truth
The most recent cause of Nia Jax being reckless and causing a minor injury was towards R-Truth.
At Royal Rumble 2019, Truth was scheduled to come out at #30 as he had won that right by winning the 2018 Mixed Match Challenge alongside Carmella. However, Truth was then attacked by Nia Jax from behind.
A female WWE star said her life is in danger. Details HERE
It's clear that the attack was planned for storyline reasons as the WWE had wanted to make Nia Jax the fourth women to compete in the Men's Royal Rumble match, but the rumors have suggested that Nia was too brutal when attacking R-Truth.
According to Jerry Lawler in an episode of Dinner with the King, he had confirmed that "she blasted R-Truth and knocked him face-first into that wall."
There were also reports that R-Truth was being held back by Road Dogg as Truth was "hot" towards Jax after she had "hurt his ankle and face" whilst the attack was occurring.
Apparently, Truth was ready to look for Nia Jax so that he could confront her, but there isn't any more information to suggest if he found her or not.
Truth also became the new US Champion on the 29th January 2019 edition of SmackDown, as he had pinned Shinsuke Nakamura and Rusev in back-to-back matches on the same night.
In the storyline, Truth had stated before the matches that the opportunity to face Nakamura was because of him losing his Royal Rumble spot.