Secure Socket Tunneling Protocol (SSTP) is a fairly secure and capable VPN protocol created by Microsoft. It has its upsides and downsides, meaning that each user has to decide for themselves whether this protocol is worth using it. Despite being a primarily Microsoft product, SSTP is available on other systems besides Windows.
This post explains VPN protocols and how to choose the right one for the best. VPN Protocols: PPTP VS SSTP VS L2TP/IPSec VS IPSec/IKEv2 VS OpenVPN VS SoftEther VS WireGuard.