i dont know why from last 2-3 days i have to use vpn to open freecodecamp.org?
Your ISP is blocking learn.freecodecamp.org (or, more likely, the service it’s hosted on). This is at the discretion of your ISP and FCC has no control over it.
Your IP without VPN might not be allowed on FreeCodeCamp or maybe FreeCodeCamp is blocking your IP. thats why it is working with VPN.