SanDisk SDSDU-008G-U46

I bought two copies of the referenced Sandisk card SDSDU-008G-U46 at Amazon there are several months.
I then identified the following performance on my system, with ATTO Disk Benchmark 2.47 in XP Pro SP3, USB 3.0 USB 3.0 drive, block size greater than or equal to 64KB:
- Writing 25.8 MB / s
- Reading 43.1 MB / s
Pleased that blithely reading was over 30 MB / s specified, I bought recently two other copies, and there surprises!
In the same configuration, for both cards, I note:
- Writing 16.6 MB / s
- Reading 43.1 MB / s
I test again the old two cards to see if anything has changed in my setup, and I fall back on good 25.8 MB / s write.
No doubt, the new maps are less efficient: 16.6 MB / s to 25.8 MB / s is a performance hit over 35% ...
Clearly, the "recipe" SanDisk has changed, and not in a good way!