Two-weight UFC champion Amanda Nunes has withdrawn from her featherweight title defense against Megan Anderson next month for undisclosed reasons, according to multiple sources.

Nunes (20-4) was scheduled to defend her 145-pound title against Anderson (10-4) in the main event of UFC 256 on Dec. 12 in Las Vegas. The UFC has not officially announced the cancellation of the bout or a new main event for what will mark its final pay-per-view of 2020.

Anderson, who is riding a two-fight winning streak and has not yet fought for a UFC championship, tweeted a series of broken-heart emojis from her account on Monday.