Image courtesy: ePhotozine.
At the Photo & Imaging 2023 event in China Panasonic managers said that demand of 8K on digital cameras is very weak and therefore you should not expect 8K to be implemented any time soon. This likely means that the S1H and the GH6 successor will both NOT have 8K recording.
If you remember back in 2017 Panasonic promised to launch an 8K MFT camera by 2020. Well, we might have to wait til the second half od this decade before this might happen :(