Thanks. It starts to work miraculously (with any of these three loaders). It looks like that this is an A/B device from the result of printgpt. Unfortunately, the OTA update reboots the system automatically (otherwise one can patch boot right after the update), but it seems possible to set the active slot to the "older" one after update, patch the other boot partition of the updated slot, then reboot to the updated and patched slot.
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