As reported here [1], it appears the unload handlers [2] are being fired when they should not be.

Expected behavior

1. Go to: https://en.wikipedia.beta.wmflabs.org/wiki/Talk:Cats
2. Click the "Reply" link appended to any comment on the page
3. Compose a reply in the text input area
4. Publish your reply
5. Notice your reply successfully published to the talk page at the level of depth you'd expect it to be published
6. Notice all "Reply" links are blue
7. ✅Close the browser tab

Actual behavior

1. Go to: https://en.wikipedia.beta.wmflabs.org/wiki/Talk:Cats
2. Click the "Reply" link appended to any comment on the page
3. Compose a reply in the text input area
4. Publish your reply
5. Notice your reply successfully published to the talk page at the level of depth you'd expect it to be published
6. Notice all "Reply" links are blue
7. ⚠️Close the browser tab; notice the following confirmation/warning dialog appears: "Changes you made may not be saved."

Please note: I have not been able to reproduce this issue reliably.

1. https://www.mediawiki.org/w/index.php?title=Topic:Vcwvt3bq03o5gv8h&topic_showPostId=vd8593amh18c3myw#flow-post-vd8593amh18c3myw
2. T240259