Comment # 1 on bug 1102224 from Stephan Kulow

Sorry. Not sure what opensuse versions you updated, but I assume it was leap
42.1->42.3 - those were minor updates and we kept compat.

But leap 15 is a major version and as such libraries disappear. You can either
recompile from source, install libmysqlclient18 from Leap 42.3 or do what most
admins do nowadays in this case: create a container for your self compiled app.