The phenomenon of not having a Chinese New Year's Eve for five consecutive years occurs in the lunar calendar due to the difference between the lunar calendar and the Gregorian calendar, as well as the rules for compiling the lunar calendar. The lunar calendar is a lunisolar calendar in which the phases of the moon are based on the moon's waxing and waning cycle (synodic month), while the length of the year strives to keep pace with the return year (the actual time the Earth orbits the sun). The lunar calendar has two types of months in length, 29 and 30 days, but they are not fixed like the Gregorian calendar.
In the lunar calendar, the big month is 30 days and the small month is 29 days, which month is the big month or the small month is determined by the rules of the lunar calendar, and the specific date of the first day of the month (New Year's Day) needs to be determined by observing celestial phenomena. When the beginning of a lunar month immediately follows the winter solstice, and the month has only 29 days, then there will be no "Chinese New Year's Eve" in this year, but directly from the 29th of the lunar month to the first day of the first lunar month.
From 2025 to 2029, there will be five consecutive years of Chinese New Year's Eve on the 29th of the lunar month, that is, there is no Chinese New Year's Eve in these five years. This is the result of the adjustment of the lunar calendar itself and the movement of the moon and the sun, which is a normal astronomical phenomenon, not an abnormal situation.