I've noticed on Edson Lopes pieces he highlights (I think) certain phrases. Not sure what he is trying to tell us when he puts a section between these arrows. Notice arrow pointing left and down, then right and down. I never ran into these arrows before. Here's an example from his transcription of Bach's Toccata and Fugue in D minor, BWV 565.
Based on their placement in the score, they appear to mark phrase boundaries. Note that they come in pairs: e.g., m. 18 has a leftward mark and m. 19 has a rightward mark. Similarly mm. 21-22.
As @OldBrixtonian points out, these marked passages are played like cadenzas, with some rhythmic freedom, which can be heard in this recording (thanks to @OwainEvans):