Maybe add a notice to the site header listing currently-running experiments. Apart from making it easier for people who don't read every post to keep up with rule changes, that'd emphasize that there's something out of the ordinary going on, and not the new normal.

PS: How do you feel about adding a "rationale" text box to the flagging process + some eventual feedback on whether moderation agrees with the flag/rationale? I basically never flag comments because I'm not sure I'm the same page with y'all.