Adding support for deprecated JS functions is something I spent some time solving in ACF v5.7.
In version 5.7.6, technically the acf.validation.lockForm() no longer exists, however, it is still usable.
The acf.validation object inherits all functions from its “prototype” which you can inspect here acf.validation.__proto__. This object does contain the lockForm() function so you can continue using acf.validation.lockForm() without any issues 🙂
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