You may find this article of interest.
How to pH Test Soap the Right Way & Why It Matters!
Particularly note this passage:
It's much easier to identify lye-heaviness through visual cues, like the presence of liquid pockets or crystallization, rather than pH testing soap. If there is an unknown liquid or substances seeping out of a soap, a pH test can help you identify if the liquid is lye solution or separated oil, fragrance, or another additive. pH testing handmade your soap to confirm a suspicion when troubleshooting is the first step in knowing how to correct it. .... However, pH testing your soap should not be used as the
sole quality control measure, as it can be unreliable.