When the igbinary module is missing, the following performance recommendation appears in Site Health:
The REST API did not behave correctly [Performance]
The REST API is one way that WordPress and other applications communicate with the server. For example, the block editor screen relies on the REST API to display and save your posts and pages.
The REST API did not process the context query parameter correctly.
When the
igbinary
module is missing, the following performance recommendation appears in Site Health:Should
igbinary
not be mentioned on Server Environment?