I've got hit by this issue AGAIN when trying to bump flash size for my units using 16MB Winbond chips, so I decided to share.
For W25Q128FVFG, the kernel unlock mechanism would not work, for some reason - despite flashrom showing the chip isn't protected, nor could U-boot autoupdate itself. I had to go back to version 5.5.9 by going through 6.0.4-beta, 5.6.15 (both through TFTP), and then to 5.5.9 using web upgrade - from then I could install OpenWrt factory image through the web interface, too. I tested on OpenWrt v23.05.2 which is known broken - so there is another option to use current release instead. Version 5.6.15 wasn't enough, I had to take the extra step down to v5.5.9.