The CMake documentation states that the default new behavior matches the old behavior but we cannot confirm this as our dependencies are built with a non-debug runtime in debug configuration. As a quick but transient solution we should use the old behavior in all projects.
We should also create a minimum prototype to show the issue and report it to the CMake devs.
https://cmake.org/cmake/help/v3.18/policy/CMP0091.html
https://cmake.org/cmake/help/v3.18/variable/CMAKE_MSVC_RUNTIME_LIBRARY.html