Change 269349 had a related patch set uploaded (by Petr.matas):
Fix T126241: #cite_note and #cite_ref links generated from empty references are broken

https://gerrit.wikimedia.org/r/269349

You should be seeing a big fat red error on that page, though, which is apparently suppressed on en.wp somehow…

@matmarex Yes, if I switch the interface to Czech language, I do see it, but in English I don't.

The patch also fixes the following problem:

Reproduction steps: Use the empty named reference twice
Expected behavior: Two backlinks are generated
Actual behavior: Only one backlink is generated [BUG]

Example: https://en.wikipedia.org/wiki/User:Petr_Matas/ref_error

In T126241#2010510, @matmarex wrote:

You should be seeing a big fat red error on that page, though, which is apparently suppressed on en.wp somehow…

https://en.wikipedia.org/wiki/Template:Broken_ref#Namespaces
"Errors on talk and other pages do not show by default but can be enabled by adding a rule to your CSS"

This was introduced in en.wp because there was no automatic <references /> insertion, so whenever people would discuss a fragment with references, you would get bit fat red errors all over the place. It was never really changed after T68860 was fixed I suspect. Maybe something that @Edokter would be interested in.

Change 269349 had a related patch set uploaded (by TheDJ):
#cite_note and #cite_ref links generated from empty references are broken

https://gerrit.wikimedia.org/r/269349

Change 269349 merged by jenkins-bot:
#cite_note and #cite_ref links generated from empty references are broken

https://gerrit.wikimedia.org/r/269349