OpenType has added CFF2 payloads, intended to replace the older CFF payload (by convention OpenType-with-CFF uses the .otf extension, OpenType-with-CFF2 will likely keep that practice) markedly improving them in terms of the quality of the outline language, with decreased file size. However, because it's still new, support for it is flaky at best: having an entry dedicated to whether or not Opentype with CFF2 is supported or not would be quite useful.