That's a nice euphemism
From "500 MB/s" (only if you're writing 0s with benchmark tools) it will drop to about 250 MB/s (write speed).
But since SF controllers have been pieces of sh** due to their extremely buggy firmwares one should avoid these anyway. Even now there are still critical firmware updates (depending on the manufacturer/distributor the customer may not be able to update it).
Back in 2011 (before that was common knowledge) I bought five 240 GB SSDs with synchronous Intel MLC NAND and SF 2281 controllers, last month the last of them died suddenly, it had only about 20 TB data written to it and the SMART status was without any cause for alarm.
BTW only buy SSDs from manufacturers that also produce the NAND chips in their SSDs and deploy firmware updates for end users (e.g. Crucial (->Micron), Samsung, Intel, Sandisk).