Thanks for the report. So it’s not a RapidWeaver Classic generated file, it’s a Stacks plugin generated file.
I don’t believe it’s malicious, it looks like it just sets a php info page for helping to debug/troubleshoot any issues should they arise.
I reckon some strict virus/malware scanners see that code and think it’s trying to maliciously enable the php info page, which if left enabled can give malicious actors information about your server environment that might make it easier to hack.
You can ask your host to add that file to their safe list, or you can just delete it if they get fussy about it.