Some common mistakes that players make in difficult levels when playing Geometry Dash include:

Overreacting to Obstacles: Players may panic and overreact to sudden obstacles, leading to mistimed jumps or movements that result in failure.
Lack of Patience: Impatience can cause players to rush through sections without proper timing or strategy, increasing the risk of colliding with obstacles.
Inconsistent Timing: Failing to maintain consistent timing in jumps and movements can lead to repeated errors in navigating through challenging sections.
Not Utilizing Checkpoints: Players may fail to reach checkpoints consistently, forcing them to restart from the beginning of the level each time they make a mistake.
Failure to Memorize Patterns: Not memorizing the patterns of obstacles and the level layout can result in unexpected collisions and failures to progress.
Underestimating Jump Distances: Misjudging the distance of jumps or the speed required to clear certain obstacles can lead to falling short or overshooting, causing failures.
Losing Focus: Distractions or loss of focus during intense sections of the level can result in mistimed movements and collisions with obstacles.