This would probably help us solve several tasks around filter privacy (see the workboard on AbuseFilter). T174862: Special:AbuseLog should not show log entries of private filters is a similar proposal, but there were some concerns about transparency. I'm not sure myself, too.

Maybe the "hidden" flag should not be boolean, but support more states: public, private (indication of existence possible, but details hidden), hidden (no indication of existence), etc. This could be a path for T234155: Create CheckUser-level abuse filters.

In T309693#7973529, @matej_suchanek wrote:

Maybe the "hidden" flag should not be boolean, but support more states: public, private (indication of existence possible, but details hidden), hidden (no indication of existence), etc. This could be a path for T234155: Create CheckUser-level abuse filters.

Good idea, definitely worth exploring in the long term. But for now, I think removing private filters altogether (thus erring on the side of caution) would be better than the status quo.

This behaviour has always been the same since the creation of AF, so I think it's very important to collect feedback before implementing the change. A possible message for Tech News could be something like:

On [[Special:AbuseFilter]], every user who can see the list of filters can also see information about private filters (ID, consequences, status, last edit), even if they're not allowed to see the private filters themselves and their rules. This has always been the case since 2009. There is a proposal to remove all information about private filters for unprivileged users. You can read more and leave your feedback at [[phab:T309693|]].

Hi @Daimona Alternatively, I'd suggest this request for feedback could be best sent directly to the talkpages of the abusefilter documentation pages. That would lead to the correct people seeing it in-situ, and reduce the distraction (and potential misunderstanding or alarm, or BEANS) among the wider movement.
Specifically, you could use this tool https://tools.wmflabs.org/wdmm/
along with https://www.wikidata.org/wiki/Q4582485 to create a MassMessage target list.
The full documentation for it is here: https://meta.wikimedia.org/wiki/Wikidata_MassMessage_tool
Does that seem reasonable? If not, and you're certain it deserves an entry in Tech News, we can do that. Cheers.

In T309693#7977145, @Quiddity wrote:

Hi @Daimona Alternatively, I'd suggest this request for feedback could be best sent directly to the talkpages of the abusefilter documentation pages. That would lead to the correct people seeing it in-situ, and reduce the distraction (and potential misunderstanding or alarm, or BEANS) among the wider movement.

I think that could work, as long as enough people see it.

Ok, I'll leave it in your hands. :-)
I'll remove the tech-news tag for now. (But as before, feel free to say it ought to be sent via this method!)