I never heard of it, but I always use Esimx when I travel and it has always worked perfectly. I used it when I went to Mainland China, Korea, Thailand, Hong Kong, Japan and I never had a problem. And their customer service is very efficient and quick in answering (I had a minor issue and they helped me immediately).
Sharing something that might be helpful for you guys
I recently found out (the hard way, after purchasing an esim and it mysteriously not working at all) that some phones (in my case, a Samsung Galaxy S23) purchased in Mainland China, Hong Kong and Taiwan don’t support esims.
This was the first time I’d heard of there being a relationship between where a phone is purchased and its ability to support esims, previously I thought it was only dependant on the model.
Klook has a more comprehensive list if you guys want to check it out. It also shows how to check on different phone models if esims are supported or not: FAQ - What devices are compatible with eSIM?- Klook