Wet plate collodion wave-like effect on the plate

[natashaphotography]

Hello everyone !
At the studio where I work, which has been doing wet plate collodion photography for a decade, a new sudden issue is happening and we aren't sure if it's related to the current summer heat, an issue with the silver nitrate, or the collodion.

Basically, once we take the plate out of the silver nitrate bath, we notice very small wave-like designs. We've tried various things like changing the silver nitrate baths, changing the collodion, changing the time we take to load the plate etc., but this is the first time we are seeing this. Has this happened to any of you before / do you know what the issue could be ? (I attached a photo to the thread to show the wave-like issue) Thank you in advance !