uneven, bite, disagree
齟 centers on things not fitting together smoothly: uneven surfaces, teeth that don't meet properly when biting, or opinions that clash and disagree.
齟 combines 齒 (teeth) with 且, which likely contributes a phonetic element and may suggest unevenness or obstruction. The exact historical development is uncertain.
Teeth 齒 that are uneven 且: imagine a row of teeth with one sticking out, making the bite uneven and causing disagreement when chewing.
For ソ, picture uneven teeth that need to be sawed straight: saw -> ソ, and the uneven bite is fixed.