Ruby Rose quitting Batwoman is an unprecedented setback for DC's well-oiled TV machine

"I have made the very difficult decision to not return to Batwoman next season," Rose said in a statement. "This was not a decision I made lightly as I have the utmost respect for the cast, crew and everyone involved with the show in both Vancouver and in Los Angeles."

Her vague statement, and the generic platitudes from Warner Bros. and The CW that followed thanking Rose "for her contributions to the success of our first season" and wishing her "all the best", gave little in the way of explanation as to why the Orange is the New Black actress had abruptly quit the superhero series.

Last year, Rose had to undergo emergency surgery for two herniated discs, but a source told Variety that her decision to exit Batwoman "had nothing to do with her health or injury", while speculation that her departure was in response to backlash from social media trolls – a factor which had previously caused the star to delete her Twitter account – also remains unsubstantiated.

Whatever the real reason, Rose stepping away from Batwoman after just 20 episodes is a blow unlike anything the Arrowverse has previously suffered in its eight-year existence.

Nothing quite like this has ever happened before, and one of the biggest questions surrounding Rose's exit is how it was allowed to happen now – US TV stars are traditionally signed to multi-year contracts from the off and the lead actors of the Arrowverse are no exception, with Stephen Amell confirming in 2018 that his original deal tied him to Arrow for at least seven years.

"The studio... has had me under contract – willingly, I signed it," Amell said during an appearance on Michael Rosenbaum's Inside of You podcast. "I have no regrets that I signed it. But every year it's like, 'We're going to pick up another season. You have to come back.'"

It's possible that Rose signed a different contract to her cohorts. As inarguably the most established name to ever sign up to lead an Arrowverse series, she may have struck a deal that could be renegotiated every year, though it's hard to grasp why Warner Bros. would agree to that when one possible outcome would be the situation in which it now finds itself – a TV show without a lead.

There may also have been a clause in her contract – and indeed in those of Amell and other Arrowverse stars – that allowed a longer deal to be terminated under exceptional circumstances, though without knowing the full context of why Rose left the series, it's difficult to speculate on exactly how and why she was allowed to walk away.

Going forward, Batwoman faces an uncertain future, unlike anything its sister series have ever experienced – despite its eight year run and the interlinked nature of its shows, recastings across the Arrowverse have actually been relatively rare, especially in major roles, and this will certainly be the first time that a lead actor has had to be replaced.

How exactly the show will vault this considerable obstacle is, right now, another unknown, though Warner Bros. and The CW have insisted that they are "firmly committed to Batwoman’s second season and long-term future" and they "look forward to sharing its new direction, including the casting of a new lead actress and member of the LGBTQ community, in the coming months".

Right now, the show's second season is still slated for a January 2021 premiere, with the postponed date giving producers a little more time to find their new Batwoman – even if any contenders (with Brooklyn Nine-Nine's Stephanie Beatriz having already thrown her hat into the ring) might have to screen-test on Zoom.

Batwoman airs on The CW in the US and on E4 in the UK – check out what else is on with our TV Guide