Security dates are super confusing. (again)
I managed to install with web installer finally (I will write a separate guide how I made it work), but web installer leaves the device unlocked, maybe because it is in “alpha” development version. And still I have to figure out the dates somehow to not brick 
the phone.
After installation, now security date is 2024-10-05, previously it was 2024-11-05. So if I would lock it now, as per instruction, it would be fatal to my Fairphone 4.
Who updated Install /e/OS on a Fairphone FP4 - “FP4” the date from 2024-11-01 to 2024-12-01 after we said its wrong? Is it updated manually by hand? It is wrong again.
That page says:
/e/OS build : T official (Security patch: 2024-12-01)
But T version is released 2024-11-08. Which is the version web installer also installed for me.
For some reason easy installer (not web installer) downloads “e-latest-FP4.zip.prop”, but it should download android of the same version number (T) as I read somewhere, also as web installer did the same as well. I manually figured out the download link. Here it is: https://images.ecloud.global/stable/FP4/e-2.5-t-20241108446629-official-FP4.zip.prop
It says security patch for T version is 2024-10-05, same as my phone also currently shows.
For such an important thing with all the warning, page should list the accurate date.