Mac Studio - Slow USBC ports / hard drives not mounting in Disk Utility and now Read Only only / Port Sparking

I have recently returned by second Mac Studio to Apple to review. My first one got replaced in May 2022. Been having several issues over the last month or so with slow USBC ports when used with external hard drives and correct cables. Hard drives are now up to 10 times slower in reading and writing using Black Magic - Disk Speed Test.

Using Disk Utility / First Aid, 8 drives now won't mount and the test fails. All drives have now been put into Read Only mode which I read recently is a Mac safety mechanism for a drive it thinks is failing. Surely 8 drives against one Mac is more likely the Mac has issues. Also seen some sparking when putting USBC cables into the Mac Studio. Ironically, when connecting hard drives individually via ports on Studio Display, the speeds are more as they should be.

Any one else had any similar issues as the Store said they can't remember the last time a Mac Studio went in for repair, but that's probably Apple speak.

Thanks, Matt