For some reason I'm no longer seeing the Ottomans expanding east & south, taking out the Mamluks.
They seem to ally nations behind them instead and focus exclusively on Eastern Europe, this is quite annoying to watch but likely more annoying to play in the area.
Edit: it's hard to tell if this is a separate anomaly or indirectly related to AI debt. Either way, the game is very difficult to get into when the AI is handicapped by such severe debt.
Also in my latest game as England, Castile (Spain) had 5,000+ in debt. They continued to expand, dragging their economy down further, even their colonial nation lost to native nations!