All traditional festivals are counted on the lunar calendar, so why is Qingming Festival on April 5 of the solar calendar?

Yes. All traditional festivals are labeled according to the lunar calendar. The twenty-four festivals, however, are counted according to the angle of the earth relative to the sun. Qingming is one of them. This method of calculating according to the earth's relationship to the sun coincides with the solar calendar's method of dating. So, around April 5 on the solar calendar happens to also be the moment when the earth is at that angle to the sun, Ching Ming. This is

The reason why the Qingming Festival is around April 5 on the solar calendar.