Hey Rakib, actually none.
I am really loving the embedded sync function. There is no native php driver for libsql(turso) so the fact that I can get sqlite file and use Laravel native methods made it a 100x deal.
I did however hit a couple "issues" when I was optimizing indices where I caused a lot of GBs to be synced (around 50GBs over the billing period). I had a call with Gauba, founder of Turso, and he was very kind to waive it and further hear me how I am using it. I wouldn't call it a limitaion.
Frankly, if it fits your use case, it's quite cheap. Although I have seen that Cloudflare finally introduced sqlite download support.
What are you building if I may?