The genus Flammula, typified by Pholiota alnicola, is not related to Pholiota and has long been accepted. It is a member of the Hymenogastraceae.
e.g. Fungi Europaei, Strophariaceaea, M. Noordeloos, 2011
For the phylogenetic position see, for example.
https://doi.org/10.3114/fuse.2019.03.05
https://doi.org/10.1080/00275514.2017.1377586
http://dx.doi.org/10.1080/14772000.2014.967823