According to thePaper.cn, over 100 restaurants have been tagged with "原法租界" on Bon App. Although widely used by the expat population and even locals, the term is considered offensive and ignorant of "national suffering", seen by many Chinese as a complacent endorsement of Shanghai's colonial past. Bon App is now suspected of violating an "advertising law" that bans its use in a commercial context, potentially facing suspension and a 20,000rmb fine. The report also states that the violation only exists online, however. It's inappropriate but "not obvious", so there might be some leniency there. Anyhow, a public apology is expected.
This is not the first time media platforms and businesses have gotten in trouble for using the term "Former French Concession", which refers to a vast and busy area that sits within the Huangpu and Xuhui districts. Pizza Express was fined in 2012 for exactly that reason, and SmartShanghai.com also got in hot water for it -- steaming, boiling, scalding hot water -- when the term was deployed as a tag/filter in our Housing section.
So yes. Let it be said now and forever: It's "Xuhui". (Or Luwan, whichever.)