What are the reasons for the logs to become invalid?

Warcraft Logs
1

in our Classic guild, our logs seem to have a dark red background which singles out everybody in the raid.
Is it because some people took the Silithus buff and it bans everyone from ranks or is it that we had too many rotations in the first week?

link to unranked logs

I cannot seem to find this information ANYWHERE. I know there were polls about this prior to Naxxramas release but why can’t I find the result of these polls?

Thanks in advance.

2

Silithus buff.