As a gift from Nash, the original Harrison Wells was reborn with the power to travel time at will. Harrison willingly puts himself in a loop of 1996 to 2000 to enjoy his marriage to Tess Morgan, being unable to alter time to save her from the crash (as Thawne would kill her anyway to keep his ruse going) and bring her to the 2020s.
This was originally supposed to be the season 6 finale, but due to COVID-19, it is was pushed to season 7.
When the Speed Force is reborn, the bolt that shoots out separated into four different colors, likely the other Forces from the comic (Sage, Still, and Strength) and leaving the fourth unknown. The fourth could either be the Speed Force itself, or the Forever Force, which a Cosmic Force that would grant one control over everything and that the wielders of Speed, Sage, Strength, and Still have gone to war over before.
To keep Ralph's recasting in-universe, his face is reduced to "mashed potatoes" from surviving an explosion of 500° and having his head in a special healing helmet, thus allowing the excuse for why he looks different when he comes back played by a new actor.
Ralph being disfigured and later leaving the team to travel the world with Sue was the result of Hartley Sawyer being fired from the show during the hiatus.