You can detect OpenResty Default Page using this tool.
OpenResty® is a full-fledged web platform that integrates our enhanced version of the Nginx core, our enhanced version of LuaJIT, many carefully written Lua libraries, lots of high quality 3rd-party Nginx modules, and most of their external dependencies. It is designed to help developers easily build scalable web applications, web services, and dynamic web gateways.
If attackers detect the technology used, they will try to detect vulnerabilities related to this application.
Only use components that do not have known vulnerabilities, only use components that when combined to not introduce a security vulnerability, and ensure that a misconfiguration does not cause any vulnerabilities.