It's very modern CSS.

Reading the article.

First Online Date: 2024-10-09

Date Posted: 2024-12-05

Date Published: 2025-02-01 (It's being "published" at a conference)

As mentioned the paper was accepted in NDSS. https://www.ndss-symposium.org/ndss2025/accepted-papers/ The conference occurs in Feb, and typically, the conference proceedings are published a little earlier than the conference itself.

That is probably the scheduled presentation date.