Not necessarily. Wine has the potential to foam any time there is CO2 in suspension, both during and after fermentation. IME, during fermentation foaming is a combination of yeast strain, how vigorous the fermentation is, the amount of solids, the amount of suspended CO2, temperature, and probably other factors.
Stirring and adding things (e.g., nutrient) to an active ferment can produce foaming as it causes the CO2 to be released. Paul (
@sour_grapes) mentioned the proper term in a recent post, although I can't think of it at this moment, but essentially the powder gives the CO2 something to cling to and it comes out of suspension, producing potentially heavy foaming.
This will also happen with a post-ferment wine that hasn't been degassed.
If you use a large enough primary, the issue is eliminated. I ferment 23 liter kits in 7.9 gallon (29.9 liter) buckets, which is (IMO) the bare minimum size. I was going to purchase 10 or 12 gallon Brutes, but my local home supply store didn't have any small ones last time I looked. I ferment grapes (up to 180 lbs) and recent triple batches of kits in 32 gallon Brutes, which is overkill, but it eliminates overflow problem.
Always add things to a wine carefully, e.g., when adding nutrient, sprinkle a bit gently over the surface to see what happens. If it foams a lot, add in small amounts until done.