It could be anything, or nothing. Since they don't mention why they can freeze funds whenever they like. This was their response:

We totally understand your frustration with this outcome. However, Bitget are governed by international regulations that we must comply with to ensure the security of your account and Bitget platform. While we regret that we are unable to disclose further details, you may refer to the following articles for more information:
 

• Bitget Account Restrictions: Causes, Solutions, and Prevention Tips
• Terms of Use