This is not to debate about the punishment itself just to know what the next step.
Either buy the the gems, quit playing or play and slowly pay off your gem debt, which might take for ever.
Personally I would take it on the chin and buy the gems
I have heard conflicting reports.
Some say limited time to repay before banned.
But if SGG let’s you play with a huge negative gem balance.
F2P can just ignore it.
SGG seems to hate giving gems and prefer merciless RNG loot or tokens.
SGG micro transactions seem to hate gems and favor summon tokens ( how many do we have since Ninja tower release? ) so not much impact.
Consider not renewing your VIP since one of the major draws of VIP is cheap gems and a huge negative balance will negate this benefit.
Big spenders can pay off the gems, just treat it like a big bundle of X sale.
In fact this is why many wealthy individuals in USA ignore traffic laws ( shout out to Anchor’s recent video ) and some European countries base fines on income.
I’ve seen stuff on Line which has an in game message saying that a negative gem balance was detected and that the player had 13 days to return to 0+ gems. If not, the account will be permanently closed.
At a guess, I would say that the system / suppoet are still catching up with all the negative imbalances.
Based on that, until you get a message just keep on playing as you will (see @Gryphonknight post above).
When / if you get a message / warning via in game mail you have two choices:
pay up and return the gem balance to surplus; or
Lose the account and either start again, walk away or find a different game.