When we released Sailfish OS 4.0.1 (Koli), we upgraded our OpenSSL libraries to version 1.1. At the same time we deprecated OpenSSL 1.0 libraries. Like mentioned in the community IRC meeting at the time, the old libraries will be removed from Sailfish OS - which means that all apps which still link against them will stop working on the new versions of Sailfish OS without the library.
While we haven’t yet decided which exact Sailfish OS release will remove the old libraries, it is quite clear that the time is approaching. Therefore we would like to ask those app developers who still use the old libraries to move their apps to the new libraries. It should be also noted, that the security vulnerabilities in the OpenSSL 1.0 libraries are not getting fixed, so using them might cause your app to be vulnerable.