If let say anki hosting is gone, do my data that i built on anki app synced on the phone disappear?
or it will remain on my app but cannot sync on my phone whenever i built new flash cards
Just need clarity since im new using Anki thank you!
You can disable syncing altogether. And if you create multiple profiles, you can only sync with one profile. But you can also transfer them to your phone via an archive. Some people even create their own servers for sharing, and it’s probably even posted on websites somewhere. So that shouldn’t be a problem. The problem with syncing is that when you’re asked where your current deck is—the most recent deck—and you choose the wrong direction…that can be painful. So, take your time, and while everything is working fine with the site, always choose Ankiweb. I’d even add an option somewhere to avoid confusion, since it’s very rare that you need to change the direction.
So everything will work even without a website. However, some people have tricky decks that download things from the internet, so I won’t speak about them. But regular decks of cards, with everything stored inside, work without any problems.
I see… thank you 
AnkiWeb doesn’t “host” your collection. Your collection exists on each of your devices – AnkiWeb merely gives you a convenient way to keep multiple copies of your collection up-to-date with each other.