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.
I think they will migrate everything to fossify. With the gallery this already happened, the SMT Gallery vanished from my phone and the fossify gallery appeared. I guess that’s a good way to go, since for now fossify is just the same thing with a different name.