Seagate One Touch 2TB: ~980 MB/s in CrystalDiskMark but only ~360 MB/s in a full-drive test. Is this normal?

I recently bought a Seagate One Touch 2TB SSD and decided to test it properly since it's a new drive.

I ran CrystalDiskMark first and got:

Read: 953 MB/s

Write: 982 MB/s

That seemed pretty good considering Seagate advertises speeds of up to 1030 MB/s.

I also ran Seagate's own SeaTools, and the Short Generic Test passed.

After that, I ran H2testw over basically the entire drive to check the capacity and make sure there weren't any errors.

It completed with no errors and successfully wrote and verified about 1.907 TB, but the speeds were quite a bit lower:

Write: 360 MB/s

Read/verification: 229 MB/s

So I'm a little confused by the difference between the tests. CrystalDiskMark looks great, but the full-drive H2testw test was much slower.

Is this normal for this SSD, or is the lower speed something I should be concerned about?

I'd especially appreciate hearing from anyone who owns this drive or a similar Seagate external SSD.