I tried to install the latest release on my Phicomm KE2p (https://downloads.openwrt.org/releases/21.02.2/targets/ramips/mt7621/openwrt-21.02.2-ramips-mt7621-phicomm_k2p-squashfs-sysupgrade.bin).
The router downloads the fw from the tftp server, but at the end, it gives this error:
Bytes transferred = 6292042 (60024a hex)
LoadAddr=84000000 NetBootFileXferSize= 0060024a
Abort: bootloader size 6292042 too big!
I tried also previous and smaller versions but with the same result.