Those scores look fine to me, and where they should be. Pefectly normal & nothing to worry about
I think the key phrase here is "up to". It doesnt mean it'll average that speed.
But, it doesn't really matter either. We are talking about Sequential Read/Writes scores, which mean very little to nothing for the OS.
Look at your 4K speeds, as thats what really counts. Far more so than the sequentials.