Vtc6m based battery, cell unbalace already while charging

hi there,
I have built a third battery for my efoil/foil assist. the first two batteries were 12s2p reliance rs50 and I am very happy with their performance.

I wanted to build a third pack but I had problems to source the same cells for a reasonable price and since I do not need many cells, sourcing them directly from china is also quite expensive.

therefore I sourced vtc6m from nkon and built a 14s3p.

already at the first charging I got a cell imbalance of 0.038v while chargeing 5A, much bigger than anything I have seen with the RS50s, therefore I would appreciate some opinions on this matter. I use the cells from 4.15v to 3.4v so i think that a bank with a little less capacity should cope with my usage but I have no experience with such a problem.

What are your experinces with something like this?

Thanks in advance!

The issue is within group 7.
I’d measure by hand with a multimeter.
Could be a bad cell, pierced cell, bad connection, anything. Best to swap it out / fix it asap while the battery is still new. Like this the age difference will be minimal.