The 2019-20 high school rules were published to the USA Cheer site on May 1 and are available here.
An update has been made to the new rule regarding signs for high school teams and younger. Bases are not allowed to hold props that are made of hard material or have sharp corners or edges. Stunts and pyramids that use these types of signs should choreograph them so that the top person comes down with the sign legally or hands them to a person on the ground who is allowed to hold signs.
The NFHS has released their current “Comments on the Rules“, which include this change as well.