This strategy of pretending to be a Japanese app has worked for a decade but now seems to be coming to an end, with the JP government looking to force Softbank to somehow broker a deal with Naver to reduce their share to less than 50%.
The EU should do similar with Whatsapp.
I would know, I literally worked there.
There has been an entire scandal about Line's data having been hosted in Korea all this time for more than a decade, after which the servers finally got moved to Japan. You're hardly going to place all physical servers in country A and then do all backend and infra development in country B.
[1] https://careers.linecorp.com/ko/jobs?ca=Engineering&ci=Bunda...
And if you think that’s preposterous you don’t know the least of it. For example, the designers in the company decided to boycott meetings.