As reported in a reddit post and confirmed in a github discussion, Simple Mobile Tools is being sold to ZippoApps which is known for shady business practices.
It is not yet clear whether they will make the app suite closed source (which would infringe the rights of all contributors since they contributed under the GPLv3 license).
In response to that situation, one of the main contributors forked the project under the name FossifyX and will continue to work on it.
Once someone exists publicly as code with an attached valid license it cannot be retroactively removed the right to use it. So only new versions could have different licenses or something.