Eastern Orthodoxy is not an offshoot of Catholicism. They were both the same church until the schism, when they excommunicated each other.

The Pope traces his apostolic succession back to Peter, but the patriarchs of the Eastern Orthodox church trace theirs back to the other apostles. Originally, the various patriarchates were co-equal, until the Roman church began stylizing itself as the "first among equals" citing some obscure passage where Jesus had a bromance moment with Peter.

The Roman church was never in a position of authority over the other patriarchates, and when the Pope began trying to assert himself that way, the other churches began distancing themselves. The actual schism happened when that tension shattered over different interpretations of one line in the Nicean Creed.

If anything, the Roman Catholic church is an offshoot of Eastern Orthodoxy, which maintained its Ecumenical Council among the various patriarchates throughout its history.

Calling Eastern Orthodoxy an offshoot of Roman Catholicism is a very catholo-centric and misinformed take. And citing Canon Law is silly, because Rome strayed further from the original Canons than Eastern Orthodoxy ever did.