Turkey has an overheated economy. It's growth has outpaced its productive capabilities. Lot of people are painting this to be primarily Erdogans fault. That is far from true. Turkeys growth is due to the combination of foreign denominated investments and loans in both domestic and foreign currencies. The Turkish Central Bank has been surpassing interest rates despite high inflation rates to keep the credit flowing. Altogether, the economy is over-levereged and it was going through a corrective cycle from January. Normal, and healthy.
That being said, multiple geo-political situations have now pushed this correction into what is likely a recession. First, there is the situation in Syria. Aside from the domestic strains and frictions, this situation puts Turkey at odds with Russia and Iran. Second, after a failed coup attempt a paranoid and defensive Erdogan has consolidated power -- this can only increase uncertainty and risk. Finally -- the straw that broke the camels back -- the recent economic policies of US towards Turkey. Tariffs, threats, and likely more (according to the administration). This led to a sell-off of the lira against the dollar and euro. This has systemic effects as it increase the cost to finance any foreign denominated debt. What that means is that all Turkish businesses need to increase costs in order to maintain present profitability levels. Without foreign intervention -- or very good diplomacy by Turkey and EU -- this is likely beginning of a recession.