Is it possible to override the block's cache context?

Problem/Motivation

After running our site for one day, the render cache has 58,000 copies of the cheeseburger menu block. It happens because the block's cache context is set to path.url, so every page gets its own copy of the block.

On our site the menu is the same on every page, so we just need one copy. Making the change below has that effect, but is there any hook I can use or other approach so I can change the behaviour without modifying the module's code?

Thanks & regards, David

  public function getCacheContexts() {
    $cache_contexts = [
//      'url.path',
    ];
    return Cache::mergeContexts($cache_contexts, parent::getCacheContexts());
  }