You are already stretching and foam rolling (right?). But like all things, your body will adapt and you will enter the land of diminishing returns. Enter Voodoo Band flossing:
After training hard for a couple decades, I've picked up my fair share of injuries and scar tissue. For example, I have an old meniscus tear from mountain biking that flairs up during long approaches and a current elbow tweak from a lock-off move on a project. Voodoo Band flossing helps maintain the fascia and my supple leopard status.
(The dirtbag option is cutting a bicycle inner tube in half.)
Mobility is underrated in climbing. Almost every time someone falls of the top of route they blame their fitness (or even worse, their strength). I rarely hear someone blame their inability to put their body in the right position in space. Lack of mobility is amplified in outdoor climbing, with the increased subtleties of real rock and when often sending comes down to the ability to maximally use rest positions.
Extreme mobility is one of Adam Ondra's many attributes that separates him from other climbers