Noticed this today, while doing regression testing on Reply tool. But, checked on Dutch wiki and it's already on production. So, not sure when it surfaced.
Steps to reproduce:
- Go to this talk page: https://test.wikipedia.org/wiki/User_talk:RYasmeen_(WMF)/sandbox
- Reply to the comments "first", "second" and "third".
- Attempt to reply to the comment "fourth" by clicking on the reply link appended to it, notice nothing happens, the Reply Tool widget does not open.