The speed test doesn't appear to be 100% accurate - but of course it's numbers on a screen and so begins the test after test to make those numbers bigger and more importantly - bigger than what someone else gotThanks..
I seen in some people reviews on another website that i may have to put it in my PC first to update the firmware to get the faster speeds

Even at the lowest benchmark (on the PS5) speeds, it still exceeds that of the internal storage solution so will be fine.
I have a 2TB Gigabyte Aorus in mine - the day after I bought it Gigabyte released a firmware with the build notes "for full PS5 compatibility". As I'd already installed and started using it I couldn't be bothered to take it out and update. Hasn't missed a beat.