Dataminer Biast12 claims to have uncovered information on a new Apex Legends character. However, this legend, Pariah, might not be the next character since other characters have already leaked, which we are yet to see.
As always, these leaks should be taken with a grain of salt. Things could change, or it may never be released.
Pariah's Tactical Ability is a Sonar Grenade, which will reveal enemies for 15 seconds. Her Passive, Aplomb Training, makes Pariah immune to her steam and stun effects, while also allowing her to see enemy health bars.
Her Ultimate is Sacrificial Romantic, which involves setting off a device that releases "a flurry of steam in all directions" but Pariah becomes unable to move. This steam causes burn damage directly to health.
In a game as focused on movement as Apex Legends is, being unable to move during the Ultimate seems a risk; but maybe that is the 'sacrificial' part of the ability. It also states that the steam is released from a "SDM device" potentially meaning that it is something Pariah can plant, instead of the ability generating from her.
We'll have to wait to see if and when Pariah is released before we can really understand the details of her abilities.