It shows as "inline" for me – possibly a transient bug?
(All TemplateData tasks automatically get added to the VE umbrella group so that they get seen and triaged along with all the other tasks.)
I created TD with "format": "block"
But in the preview page is written "This template has custom formatting."
Reopening, since I'm currently seeing the "custom formatting" on the page of the description.
Same problem but with format: "block" (this happens with all our templates with TemplateData), MediaWiki 1.30
In fact, VE added a lot of unneeded parameters as "inline" when someone edited the page with that template: https://www.wikidex.net/index.php?title=Ruta_212&curid=15422&diff=2168365&oldid=2117685
Related issue to this: this message uses some icon that does not exist in OOUI and therefore is invisible in interface and pushes the text off-center. Someone really needs to get to this and fix both issues (since it is a smaller problem, I don’t think it needs a separate task, just that this one should be fixed someday).
I haven’t tested the patch above, but it looks to me like the problem is happening because isset( $formats[$data->format] ) was referencing an unknown variable, so it always returned custom. If anyone could check this, it would be more than appreciated.
What exactly is, the one in the topic or the one I fixed with it? The one in the topic is still present in wikis, so it’s not in any way an old issue. TemplateData should not display a message about ‘custom format’ on _every_ format, otherwise the message should be removed entirely.
Same with the icons: if an icon isn’t needed at all, then we should decide to remove it entirely, because right now it is displaying an entirely empty element there. Adding ext.templateData.images module should fix this.