It does not look like Alexa Bliss will be back in action before the end of 2021.
In response to a fan question asking her when she will return to the ring, Bliss simply stated, "Need time to heal." She also included a black heart emoji. The tweet implies that she's not ready to return to the ring.
Bliss was written off WWE television in September at the Extreme Rules pay-per-view. PWInsider reported that she was scheduled to undergo sinus surgery and the exact timeframe for her return was not known.
Bliss last wrestled a match against Charlotte Flair and there were hints being dropped that Bliss might revert to her previous character before she aligned with Bray Wyatt or another incarnation of the character she's been portraying for the last year.
There have been no hints of Bliss returning anytime soon but it's possible that they want to hold off until the new year. The Royal Rumble could be a possibility since she would get a big reaction in front of a stadium crowd.