If other devices (with the latest LineageOS) show a different security patch level, like this app,According to their web page https://opensource.srlabs.de/projects/snoopsnitch
the Snoopsnitch app is an :
"Android application for Android security patch analysis and detecting mobile abuse: Network insecurities, evidence of IMSI catcher, SIM card attacks, and SS7 abuse."
The app was updated on 01.02.2020, so I do not know what to believe... and it's open spurce.
then it can only be due to this app or device brand ( device support ) or LineageOS. I can't imagine anything else.
Maybe someone could determine this with another smartphone with the latest LineageOS.
The last rom definitely has the last synced source of LineageOS with security patch level march 2020.