This is not a bug. The pages really are transcluding themselves, as a consequence of a recent change to the CS1 module system.

<removing link to topic on enwiki; the flow extension has since been uninstalled>

I don't think that such an extreme measure is a good idea; many users (including me) use CSS displaytitles on their userpages. Perhaps a better idea would be to ignore specific CSS properties.

Special:UserLogout isn't blacklisted; the entire special namespace is

See also T217217, an identical bug for visual and 2017 wikitext editors

The example I provided doesn't work anymore, because the page was protected, but the bug still exists

Strangely, this doesn't trigger when moving a page to a title that is just protected against creation.

Extension is archived

($wgEnableAPI no longer exists)

In T203293#4566886, @Arlolra wrote:

... the comment in the module expects the contents to have been rendered.

-- get an already rendered table from whereever <nowiki>...</nowiki> put it

There is some potential for an infinite loop here. What if someone tries to substall a template that is unsubstified, for example.

This seems to me to be a duplicate of T199852, except with more complicated reproduction steps that involve an actual template in use.

Viewing https://en.wikipedia.org/wiki/Special:Log/move?page=Talk:C_Real also errors in this case.

<removing myself as asignee from former GCI task>

Not interested

Unnecessary feature bloat