Here, HY analyses cherry picking and mistranslations from Timothy Grose (Twitter thread) and illustrates the difficulties of simply grabbing words from signs without addressing the context.

Timothy Grose presents several images intended to show the existence of detention centres. This is directed originally at Roderic Day.

Note the 看守所 on the sign behind the officers, highlighted by HY.

HY comments: “Further down in the Dec thread, there is a reference to terminology including 看守所. When looking at the photos Grose posted, I had to do a double take, because the separate term 监管支队 is mentioned first, and only in a storified passage later is 看守所 mentioned.”

(For English speakers: 监管支队 means “supervision detachment”, 看守所 means 'detention centre')

As HY points out, “First, what is the relationship between 监管支队 and 看守所? This isn't clear-cut, one Zhihu says says it can be assigned to BOTH 拘留所 and 看守所; this edu site says it cannot? (拘留所 = lockup)“
“Regardless, what is the purpose of a 看守所? No, it is NOT exterior to legal frameworks ('extrajudicial', as someone in the quoted Dec thread seemed to imply), but it CAN hold suspects for far longer than 15 days.”

(Red section highlighted:
Yellow section highlighted: )

HY: “Referring back to 2nd tweet, the passage claims the Jiangsu officer was in the Aksu Central Detention Centre (阿克苏中心看守所). The problem is, are the 480 detentions from the prefecture (阿克苏地区, 2015 pop 2.5M) or the county-level city (阿克苏市, 2020 pop 695K)?”
“I managed to find an original case record link in Uqturpan County (乌什县) Prosecutor's Office mentioning the 阿克苏中心看守所.(en. Aksu Central Detention Centre)

“Apparently, someone was sent to the “central detention centre”, suggesting it possibly holds suspects from across the entire prefecture, which I am inclined to believe from the “中心” designation, not something like “阿克苏市看守所” if it only handled Aksu City.”