This is a plugin for OBS Studio that allows Vulkan/OpenGL applications to be captured. For instructions on how to use, see this page.
For this plugin to work you also need the corresponding tools to start the application with. These tools are available on Flathub as org.freedesktop.Platform.VulkanLayer.OBSVkCapture.
This flatpak is an extension for OBS Studio and is therefore not listed on the Flathub website.
To install this plugin you need to run this command in a terminal:
flatpak install com.obsproject.Studio.Plugin.OBSVkCapture