MacBook Pro usb-c speed switching from 3.1 to 3.0 bus causing playback issues in Final Cut Pro X

The device is a Samsung 860 QVO 2TB connected via a SATA 3 to USB-C connector. In these two screenshots you can see the speed difference 480 Mb/s (megabits) vs 5 Gb/s (gigbits) which changes to the slower speed randomly, then if I switch the port it is connected to the speed is fixed again then randomly it might switch to the slower speed again but sometimes it stays full speed for a while.

Another identical 2TB SSD has the same issue (but with which it seems to happen less) with the exact same connector but the exact same USB-C connector does not have the same problem in an older mac using a standard USB-A 3.0 adapter.

To me it sounds like the PCIe internals of the MacBook pro have a limited amount of bandwidth and it is allocating them randomly, otherwise the connector or SSDs are at fault but I don't see why if it's working fine on another MacBook.

The other connector I have is a caddy with a SATA to USB 3 header to separate USB-C cable which doesn't have the same problem. The only thing is the original connector the topic was about seems to work fine currently too, or was for about 30 minutes until the battery went to about a quarter and the fans ramped up then the connector went back to USB 2.0 speeds.

So either the connector has some problem or just isn't fully compatible with the way the MacBook pro usb-c ports work. I have a feeling it could also be to do with power draw or the computer thinking it is a charge cable but I am not entirely sure. Some similar sata to usb-c connectors include ac power so that could potentially be what it is.

For interests sake the direct SATA to usb-c connector reaches 60MB/s and 100MB/s faster than the SATA to usb 3 caddy with the same SSD.

The solution maybe is to make sure MacBook is fully charged and charging while using the SATA to USB-C connector.