It can't be turned off. It's entirely based off the length of the URL during a search being less than 2083 characters. This is set based off the maximum allowed by internet explorer, which today probably isn't as relevant and this can be increased now. Chrome for example has a maximum limit of over 100,000. We'll probably need to do a simple useragent test and just handle this per browser roughly.
forge.joomlapolis.com/issues/8048