Flashpoint on their download page says that it needs Visual C++ 2015+ Redist. Did you install that? You absolutely shouldn't install 2015 (actually any version from 2015 to 2019) tho, it's ancient and superseded by vcrun2022, but it doesn't hurt to install all of them with:
# note: vcrun2022 covers vcrun2015+vcrun2019
winetricks -f -q vcrun2003 vcrun2005 vcrun2008 vcrun2010 vcrun2012 vcrun2013 vcrun2022
Now, if you installed vcrun2019, and the app is compiled with vc2022 sdk, the app will behave erratically, and uninstalling it in wine is non-trivial, so the prefix is borked and have to be regenerated... It's beyond me why winetricks provides those.
Wine's Mono should be enough to run any dotnet app below Core 6~ as is, their wiki website says it's fine to use it, so you really shouldn't install M$ dotnet anyway until there's at least major breakage in functionality.