On October 15, the Missouri legislature and the Secretary of State filed a federal lawsuit to invalidate the ongoing referendum petition on U.S. House districts. Missouri General Assembly v von Glahn, 4:25cv-1535. Here is the Complaint. It says the U.S. Constitution, Article One, provides that only state legislators and congress itself can write election laws relating to Congressional elections.
The case is assigned to U.S. District Court Judge Zachary M. Bluestone, a Trump appointee.
The Complaint admits that the U.S. Supreme Court ruled in Arizona State Legislature v Arizona State Redistricting Commission that this theory is wrong, but says that case was different because the Arizona Constitution itself permitted an independent redistricting commission. This is a weak argument, but it shows how badly the Missouri legislature wants to undermine direct democracy.
In 1922, the Missouri legislature passed a U.S. House redistricting plan and the voters circulated a referendum petition against the plan, and voted it down. Therefore there is precedent that the referendum can be used in Missouri to reject districting plans.