On February 2, the Missouri House passed HJR 43. It is a proposed constitutional amendment to require statewide initiatives to pass with 60% of the popular vote. If the bill passes the entire legislature, it will be on the ballot as a ballot measure in 2024.
The measure is worded so that the first sentence says the measure would require voters to be U.S. citizens. The language about raising the vote threshold to 60% follows, and is therefore less visible. Thanks to Ken Bush for this news.