Asuka was not allowed to use the armbar at WrestleMania
During WrestleMania 34, fans did not see Asuka use an armbar move and Wrestling Observer reported it was because WWE asked her to reserve the move for Ronda Rousey who made her WWE debut. Asuka used different submissions in her Smackdown Women's Championship match with Charlotte Flair but she lost via submission which ended Asuka's streak.
Asuka had been using the armbar since Rousey showed up at WWE Royal Rumble but last night that was not the case. She also utilizes "The Asuka Lock," a body locked crossface chickenwing. This has served as her primary finishing move since her time with NXT.
Ronda Rousey used armbars to win most of her twelve mixed-marital-arts wins which usually came in the first round. At WrestleMania 34, Rousey used a armbar on both Triple H and Stephanie McMahon and ended the match by seemingly breaking McMahon's arm.