The <param> element can be used to specify parameters such as a URL (via params named "movie", "src", "code", "data", or "url") to a containing <object> element. Given the removal of plugins from the web platform, and the relative lack of use of this particular functionality, it is being deprecated and removed.
Given that plugins are gone from the web platform (with their full removal from the spec being tracked in https://github.com/whatwg/html/issues/6003), it is not useful. In some browsers it can be used to figure out the URL of an <object>, even when that <object> is not being used for a plugin, via params named "movie", "src", "code", "data", or "url". But we decided to remove this behavior from browsers instead of specifying it. This retains the HTMLParamElement interface, as well as the parser behavior of <param>.
Specification currently under development in a Working Group
Status in Chromium
Consensus & Standardization
Search tags<param>, <object>,
Last updated on 2022-04-23