An issue was discovered in Qt before 5.15.14, 6.x before 6.2.9, and 6.3.x through 6.5.x before 6.5.1. Qt Network incorrectly parses the strict-transport-security (HSTS) header, allowing unencrypted connections to be established, even when explicitly prohibited by the server. This happens if the case used for this header does not exactly match.
https://lists.qt-project.org/pipermail/announce/2023-May/000414.html
https://lists.debian.org/debian-lts-announce/2024/04/msg00027.html
https://github.com/qt/qtbase/commit/1b736a815be0222f4b24289cf17575fc15707305