There's a reason why Iris got her time sickness, and the final big bad of Season 8 is the person who did it. Deon, the Still Force'savatar, has gone rogue and the Still Force is also suffering from the time virus.
There are two big questions that need to be answered, one of which is who is the big bad behind all of this. While there is still a lot of unanswered questions, it has been confirmed that by the end of the season, time sickness will be solved. The time-sickness was first set up towards the end of The Flash season 7, which has played a bigger role this year as Iris has now completely disappeared and will be gone for a few more episodes. The Still Force was part of the New Forces created by Barry and Iris in The Flash season 7.
There is a theory online that suggests that the Reverse-Flash is responsible for the new big bad.
The Deathstorm saga came to an end a few weeks ago, but The Flash season 8 is still tackling one of its big remaining storylines, which is Iris' time-sickness.
It's not clear where her character is right now, even though she has confirmed that she will be back in the 19th episode. It wouldn't be shocking if it happened because of Eobard's hatred for the Scarlet Speedster. The next villain for season 8 will be connected to the time-sickness storyline of Iris West-Allen.
On Wednesday, June 8, The CW will show all-new episodes of The Flash. The season began with the special Armageddon 5-part event, as Eobard Thawne tried to defeat his rival once and for all. In the latest episode, it was revealed that future iris is still alive and well in the West-Allen's timelines, but the present iteration is still missing. A new version of Deathstorm has been one of Team Flash's deadliest enemies. In the recent edition of TVLine's Inside Line, a fan asked if there was anything they could tease about the next major enemy. It's not known if the speedster villain worked alone or with a new enemy that will be the actual villain. At the end of Armageddon, Eobard lost his speed and is locked up. Barry Allen and his team have been through a lot this season. You will learn why this is happening.