Previous time when I performed OTA update it was seamless. I didn't even notice the difference before and after the upgrade. Updater said that the build has been installed and that I can delete it.
the problem happened only after the last OTA update build 20210620. I was able to sideload that zip and was able to get it recovered but Magisk and MicroG were not working anymore. I just performed factory restore from the Lineage Recovery and got Magisk reinstalled through built-in method.