Here is a French Article about it.
Basically, old varnish got banned, new varnish didn't get tested, directors said let's roll with it nonetheless.
Said directors are now fired for shaming himself and France.
3 lead Head got chopped off, the French way.
They are now trying to find a good varnish that will work and will replace the medal.
Everything will be of course be payed by the French taxpayer, aka, me.
It's the good old cutting corner for short term profit thing we see everywhere nowadays.
PS: The bronze being of good quality is why it's deteriorating(aka oxidizing). The varnish that supposed to stop that is shit.