I was at ACI and I sit in front of the Canadian group like Nam for the FS, and I felt like my eardrums were going to fall off because they were trying so hard to compete in cheering, they would constantly shout "GO KEEGAN" even when he wasn't doing anything, and would even cheer louder for him when people were cheering for Yuzu. The audience in my area will also constantly cheer for anyone who skated in front of us, the loudest cheers were for Camden, Kevin, Jun, and of course Keegan. The random cheer you heard might not be for Yuzu, but for ANYONE who jumps. For the short program I sat in a different area, specifically behind a group of people who would cheer for everyone EXCEPT for Yuzu, some lady was even talking crap about him, saying he's regressing as a skater. In Japan National this year, there are tweets spreading around saying they are going to boo or distract Yuzu when he's skating, and there has been proof of it happening in the past. So yeah, I find no problem in cheering for Yuzu especially when I witness first hand what other skaters' fans did when all we do is being supportive for every skater even if we are cheering louder for Yuzu.