NEW: I don't know what is happening exactly, but various Turkish-backed Syrian rebel ('opposition') factions seem to have randomly started annihilating each other in northern Syria

@Middle_East_Spectator

Adding, this was reported too:

Heavy fighting has broken out between Suqour al-Sham Brigades and Sultan Murat Division, two different factions within the Turkish-backed Syrian 'opposition'

Just several days ago, a multitude of different anti-Assad armed factions were planning a joint offensive against Aleppo. Now they are fighting each other in northern Syria.