The one on fi.mirror.armbian.de should be the most recent. On other mirrors, the most recent linux-u-boot-odroidc2-current has a timestamp of 2024-02-29.
At the least, these mirros are all out-of-date: mirrors.jevincanders.net, armbian.tnahosting.net, mirror.dotsrc.org, armbian.lv.auroradev.org, au.sbcmirror.org, armbian.hosthatch.com