It's not in the announcement, but I did find an interview on D23, where they talked with a member of the Imagineering team about Splash Mountain and he said that they had been talking about changing it for over a year. So you were right, I apologize.Yes, there is.
The official announcement indicates that this reskinning plan for Splash Mountain has been in the works for an entire year, and other reporting on the project has indicated that it may have been in the works beginning 3 years ago.
Disney had already been planning to change Splash Mountain's theme long before people started signing a petition asking them to do so, and long before the deaths of George Floyd and others prompted this uptick in protests over racial inequality and race-based controversy.