Sharing Failed Error: A weird error that simply wastes time

hello, I face a weird issue which is not stopping my work but is massively wasting my time.

I use M4 Mac mini that I bought just for FCP work. It only has FCP installed. and "No", I have not installed chrome either :-)

Samsung T7 external SSD. 1TB. 50% full.

For sharing my project in HEVC 10 bit, 2 hours ( expected output file size of 17GB ). I keep getting errors like the one attached image. Sharing failed at some point.

I do nothing, and simply restart the process, and then I get this issue again at a later point.. and eventually, sharing finishes after multiple iterations. so I can still share but a few hours worth of sharing process takes days as I have restart the process again. no complex event or effect has been added on those clips. just stabilisation and a few text, and a background music. something that I ave always done.

file output from Lumix S5 and S5M2.

any idea what's happening??

ETR report attached. I ran ETR report whilst FCP is still sharing. otherwise space wise, I am ok.