No. The Antiochian Church is a fully canonical Orthodox Church. Antioch is one of the Five Ancient Patriarchates. Their withdrawal along with Bulgaria and the criticism poring in from many of the other autocephalous churches is presenting an existential threat to the Pan-Orthodox Synod. There will to have to be changes made or the council is going to be a dead letter before it ever meets.
taking a look on Wikipedia and some other sources, it does not seem like a big deal.
The Bulgarian Church is an ecclesiastical joke. NO ONE cares what they think about anything including the time of day.
But this objection is coming from the Antiochians and MUST BE taken very, very seriously.