The film was meant to be the start of a new series of X-Men films that would star the new younger cast (Jean Grey, Cyclops, Nightcrawler, Storm, Mystique, Beast, Quicksilver, Jubilee, Dazzler etc.) following their introduction in the past few films, but the critical and financial failure of this film along with studio merge with Walt Disney Pictures means that those plans were forcefully abandoned. Any further X-Men films will instead be a part of Disney's Marvel Cinematic Universe.
The film's budget was set to be much smaller than the previous film, due to the box office under-performance of X-Men: Apocalypse (2016), and executives even went as far as to initially plan to release the film directly to home video and streaming. The film was ultimately released in theaters and lost the studio almost $120 million as the second lowest grossing X-Men film of all time, only beaten out by Les Nouveaux Mutants (2020), which was released during the COVID-19 pandemic.
This is the first X-Men film to not feature Wolverine in any capacity due to Hugh Jackman (who had played the character since X-Men (2000)) retiring from the role in 2017.
Mystique and Magneto were not originally intended to appear as Jennifer Lawrence implied in several interviews that she was done with playing Mystique, though she said in an interview that she had a change of heart as she didn't want fans to be confused if her character got the 'Chuck Cunningham Syndrome treatment' (where a character simply vanishes from a feature, named after the removal of Chuck Cunningham in Happy Days - Les jours heureux (1974)).
The film takes place in 1992, the year the X-Men comics were relaunched with new costume designs and a new cartoon show, X-Men (1992).