This is fairly minor but still annoying and easy to fix.
I just updated F360 and during the update process, put Fusion in the background and looked at a few web pages.
Fusion brought itself to the foreground no fiewer than five times during the update process (and twice more just now as I was writing this sentence). More annoyingly those were all for things that required no user interaction.
It's just of a matter of politeness not to steal focus unless you're sure it's what the user would want (and, in my case, that'd be never).