Sorry I don’t, I just know from experience and talking to other people in different regions with the same experience.
If you want personal anecdotes, these are things that I know happen at scouting groups (not all, but enough for it to be a systemic issue): sharing hitler memes and memes about jews or other minorities, social acceptance of making jokes about jews or other minorities, collecting nazi memorabilia and roleplaying with them, doing roleplay games where the younger kids are put in pretent internment camps. Everyone I’ve talked to who’s been in scouting has been a nightmare to talk to about social issues because they actually believe in racist tropes.