The brokerage would have to comply with the SFA '_Securities and Futures Act', _which is a statute that governs the 'regulation of activities and institutions in the securities and derivatives industry, including leveraged foreign exchange trading, of financial benchmarks and of clearing facilities, and for matters connected therewith.' (SSO, 2020)
In a nutshell, they have to follow a bunch of rules.
Tiger Broker has their customer's assets kept at a separate bank and a custodian broker, also does not commingle with other investors' assets. In the event, if they were to really go bankrupt, your assets will still be safe and sound with the bank or the custodian broker.
Tiger Broker is backed by several prominent institutions like Xiaomi and IBKR, don't really have to worry about it :)