LibreOffice 7.4. was released in August 2022. Can you try a newer version, maybe 24.8 that was released 2 months ago? It is about 2 years of development. Meanwhile, maybe your problem is solved.

I installed 24.8.2.1 via flatpak.
Same issue. LibreOffice Impress does not recognize the second monitor. I can drag the Presenter console to the second monitor. When I exchange, the screens do swap, but Presentation display stays the same size as the original monitor, does not fill the new screen size.

I also notice in my terminal window on the Rasp-Pi where I launched LibreOffice:
 Failed to open display
 libpng warning: iCCP: CRC error
 libpng error: Error reading

I found this in
https://opengrok.libreoffice.org/xref/core/vcl/source/filter/png/PngImageReader.cxx?r=92067587#44

void lclReadStream(png_structp pPng, png_bytep pOutBytes, png_size_t nBytesToRead)
31  {
32      png_voidp pIO = png_get_io_ptr(pPng);
33  
34      if (pIO == nullptr)
35          return;
36  
37      SvStream* pStream = static_cast<SvStream*>(pIO);
38  
39      sal_Size nBytesRead = pStream->ReadBytes(pOutBytes, nBytesToRead);
40  
41      if (nBytesRead != nBytesToRead)
42      {
43          if (!nBytesRead)
44              png_error(pPng, "Error reading");
45          else
46          {
47              // Make sure to not reuse old data (could cause infinite loop).
48              memset(pOutBytes + nBytesRead, 0, nBytesToRead - nBytesRead);
49              png_warning(pPng, "Short read");
50          }
51      }
52  }