Firefox 64 has removed the most of
-moz-appearance CSS property values that are not supported by other browsers nor standardized in the spec. Those were mostly for internal use within the Firefox user interface written in now-deprecated XUL. Given that the
-webkit-appearance property has been supported as an alias of
-moz-appearance since Firefox 63, this removal affects
-webkit-appearance as well.
The removed values include
menulist-text, which were the most used values according to Mozilla developers. The remaining values include
none, which is often used to disable the default style of native form widgets.