Bad block table found at page 65408, version 0x01

running two RT-AC66U with Firmware-Version:3.0.0.4.270.26 (Merlin build).
one in AP mode, the other in media bridge mode.

in dmesg of AP:
NAND device: Manufacturer ID: 0x92, Chip ID: 0xf1 (Zentel NAND 128MiB 3,3V 8-bit)
Bad block table found at page 65408, version 0x01
Bad block table found at page 65344, version 0x01
nand_read_bbt: Bad block at 0x050e0000
nand_read_bbt: Bad block at 0x07fe0000
Creating 3 MTD partitions on "brcmnand":
0x00000000-0x02000000 : "trx"...

Bad block table found at page 65408, version 0x01