So I reckon the USB grabber is my capture card as that is powered by the Pi via a USB cable.
I managed to get the capture card to show up and everything worked for about 20 minutes and then boom, the screen went black again.
This is in the log. The part where it says ERROR is when the screen went black
2022-07-24T16:31:27.344Z [HYPERHDR] (DEBUG) (HyperHdrInstance.cpp:550:handlePriorityChangedLedDevice()) priority[255], previousPriority[240]
2022-07-24T16:31:27.345Z [HYPERHDR] (ERROR) No source left -> switch LED-Device off
2022-07-24T16:31:27.346Z [IMAGETOLED] (DEBUG) (ImageProcessor.cpp:180:setHardLedMappingType()) set hard led mapping to multicolor_mean
2022-07-24T16:34:31.744Z [WEBSOCKET] (DEBUG) (JsonAPI.cpp:1090:handleLoggingCommand()) log streaming activated for client ::ffff:192.168.4.22
2022-07-24T17:00:30.037Z [WEBSOCKET] (DEBUG) (WebSocketClient.cpp:30:WebSocketClient()) New connection from ::ffff:192.168.4.23
2022-07-24T17:00:30.038Z [WEBSOCKET] (DEBUG) (JsonAPI.cpp:85:handleInstanceSwitch()) Client '::ffff:192.168.4.23' switch to HyperHDR instance 0
2022-07-24T17:00:40.270Z [COMPONENTREG] (DEBUG) (ComponentRegister.cpp:50:handleCompStateChangeRequest()) Disable Hyperhdr, store current component states
2022-07-24T17:00:40.274Z [COMPONENTREG] (DEBUG) (ComponentRegister.cpp:36:setNewComponentState()) Hyperion: disabled
2022-07-24T17:00:40.272Z [COMPONENTREG] (DEBUG) (ComponentRegister.cpp:36:setNewComponentState()) Blackborder detector: disabled