Only that the app was never really under open source license, at least not since 2019. It used to be under CC BY-NC 4.0 but then it changed to a "source available" type of status [0], where any modification, redistribution etc was prohibited. The previous author explained "Unfortunately I had to apply these restrictions in the license, as people started to redistribute my app to the appstore" [1]. I do not judge the fact of stopping open sourcing it, but he did not stop advertising it as "open source". Even now, that the source code is not even available any more, its website calls it "open source" [2].
[0] https://github.com/raivo-otp/ios-application/commit/03791edd...
[1] https://opensource.stackexchange.com/a/13801
[2] https://raivo-otp.com/