“EPSG:4326” or “WGS84” use the latitude first, longitude second axis order.
“EPSG:4326” or “WGS84” use the latitude first, longitude second axis order. According to the WCS spec for 1.1, some CRS have inverted axis box: 1.0.0: minx,miny,maxx,maxy 1.1.0, 1.1.2: OGC 07-067r5 (WCS 1.1.2) referes to OGC 06-121r3 which says "The number of axes included, and the order of these axes, shall be as specified by the referenced CRS." That means inverted for geographic.
Reference to QGIS: https://github.com/qgis/QGIS/blob/final-3_10_2/src/providers/wcs/qgswcsprovider.cpp#L674 Parameters descriptions can be also found here: https://mapserver.org/ogc/wcs_server.html
This class holds all the information necessary to construct a response to a WCS request