[Plugin: Akismet] Were some major changes made recently?

I just updated from the 2.5 development version, updated akismet, and now am getting loads of spam in moderation instead of automatically filtered.

Were there major changes that would require re-training, or is it just a coincidence that the spammers changed their tactics at the same time? It looks like bog-standard “online casino” spam to me.

https://www.ads-software.com/extend/plugins/akismet/