Id also say it isn’t the flushing
Overfed plants as other say can be very harsh and hard to keep lit, and it can be very hard to flush and cure.
Not saying overfeeding was the case, if you never got over 1.6 Ec. I got my small moms at 1.6 Ec atm. and used to run some strains all the way up to 2.8-3.0 Ec in DWC years back, cut back on food 2½ week before harvest. Slowly deluting the solution, and let it run on pH adjusted tap water the last week.
I found this would be time enough for the plants to use up the nutes buildup, and they will yellow up real nice in the last week.
If not the best way to flush overfed plants, is by osmosis and simply bomb your plants with a crazy high Ec nutrient mix. This will drain the nutrients from the plant, but it will not create the same sugars in the leafs.
I found it can effect the flavor, if possible just keep them on pH adjusted tap water and let them yellow up natural.
But it will not taste harsh, burn bad or something like that.
Not helping at the stage after harvest, id try to water cure a small amount in RO water. Redry, cure and see how that turn out. If it’s salts from overfeeding, the watercure should help alot. And you will know, if thats the case.
Only smoked water cured bud once, didn’t like it. SO can’t recoment it, for anything but a way to test for left over salts.