And so do the expensive SSDs. Usually writing the first 30% of the available space goes through fast pseudo SLC mode and then the speed falls down drastically.

The most in depth SSD reviews I've seen are on this YT channel: https://www.youtube.com/@prossd

They are in Russian, but subtitles are available.

LTT just did a video on this, looking at the latest gen PCIe drives and found similar results https://www.youtube.com/watch?v=jnMMtbVP0ps