As of November 2019, OVH is listed by The Spamhaus Project as the world's
second worst Internet service provider for the proliferation of unsolicited bulk E-Mail
I can't speak to reports but I can testify about server logs. OVH IPs have been a top source of spam and attacks against my (US) (<10) servers for most of a decade. I'd add Digital Ocean to round out the top 2 list.
If a firewall goes offline for 60 seconds, I will get hammered from OVH/DO networks. Not exclusively but they're the standout kings. Just think Psychz networks, but scaled up.
I know OVH's size plays into that. But size here is less about the number of net blocks and more about their bureaucratic disinterest in abuse (common to larger hosts, inc hosts I like).
There are comparable sized hosts in the US (AWS, Azure) but when it comes to crapty traffic, OVH makes them look small and insignificant[1].
Unlike moderation at scale, known attacks are often qualifiable, detectable patterns. Can we please care enough to notice & maybe eventually, one day interrupt them?
[1]disclaimer: Spam from Google/Azure & malicious SMTP traffic from AWS totally dominated the first ½ of this year. IDK why. It's since died off - which differentiates them from OVH/DO.