ASASSN-22ak: very rapid fading!
Josch Hambsch has reported further observations. Although no definite superhump signal has been detected, the object suddenly faded by 1.8 mag on Dec. 29 (probably more than 2 mag/d since there was no hint of fading during Dec. 28 observations). This fading supports my second interpretation as an AM CVn star. The object is still expected to be detectable and please continue observations.