You can downgrade to v22j from v30a using LGUP program applied my patch for pie firmware from the following link.
https://drive.google.com/file/d/1-CDbYx1gd2i2f3zuH_uJOHPIRFq4-yRd/view?usp=drivesdk
p.s. I used the method from the thread in the forum for the other device to patch the dll file and...