Warning: Spoilers for the Legends of Tomorrow season 7 finale.
Nate has bid farewell to Legends of Tomorrow at the end of season 7, but that may have come at the cost of creating a curious plot hole regarding the character's background. Legends of Tomorrow season 7 concluded with fewer episodes than previous ones, and the show is now awaiting confirmation on whether it will return for season 8. While the Legends of Tomorrow writers didn't know if it would get another season or not, they decided to end the season on a major cliffhanger in the season 7 finale "Knocked Down, Knocked Up." The Legends are now under arrest for their crimes against time and will no longer be able to count on Nate Heywood, a.k.a Steel, to help them.
Between the final battle against evil Gideon and the surprising reveal of Booster Gold, Legends of Tomorrow saw its long-time cast member Nick Zano make his last appearance as a series regular. Zano had joined the cast of Legends of Tomorrow during season 2 and to this day had been one of the show's most important characters. Introduced as a historian with a particular interest in the Legends, Nate evolved into a superhero after having a serum injected into his bloodstream by Ray Palmer. Nate would eventually follow in the footsteps of his grandfather, the Justice Society member Commander Steel.
In addition to his connection to a hero from DC's Justice Society, another important element of Nate's background was the fact that he was a hemophiliac. By his parents' decision in an attempt to protect him, Nate was never allowed to go outside and ended up dedicating all his time to his studies and his Indiana Jones movies-inspired love for history. If not for spending so much time indoors, Nate would never have become a historian and therefore would never have joined the Legends. Even though this is such a crucial part of the character's history, the season 7 finale of Legends of Tomorrow seems to have forgotten it. In an attempt to save Alun, Nate was hit by an explosion of mustard gas and had to sacrifice all of his steel powers to keep his skin from being completely burned. However, even with multiple cuts and bruises on his now unprotected skin, Nate seemed to have no problem related to his condition, undermining his being a hemophiliac.
It's possible that the Legends of Tomorrow season 7 finale simply forgot about Nathan being a hemophiliac. Six seasons or 94 episodes after Nate's introduction, the number of storylines and plot twists in Legends may have left such an element of Nate's background behind, though that would be a fairly significant oversight considering how it shaped him. It could also be that the writers simply hoped that audiences wouldn't pick up on the contradiction in order for Nate to have a more dramatic moment in his sendoff episode. However, there is a possibility that Crisis on Infinite Earths altered this particular aspect of the character as it did with many other characters and events from the Arrowverse shows. Another possibility is that after Nate died and was resurrected in season 4, his condition was reversed.
Whether it was a mistake or an unexplained retcon, the finale of Legends of Tomorrow upended a key element of Nate's character. In addition to the possible plot hole, the departure of such an important character from the Arrowverse also left much to be desired as it was rather unceremonious. If there's a chance of audiences getting to see more of Nate and his life without powers, even if just as a special guest in future seasons, it all depends on Legends of Tomorrow being renewed.