The version 20231214 (6) from https://download.silicondust.com/hdhomerun/hdhomerun_mac_20231214.dmgThat's an older version, 20231214, and it too has an expired certificate.
has a valid certificate.
The AppStore version 20240708 (11) has an expired certificate, but works in Sequoia 15.1.I'm running version 20240708, installed via the App Store last July, and the certificate expired last August.