If he's let go before 4/30/2022, the buyout is $50k for each month remaining. If he's let go after 4/30/2022, the buyout goes up to $65k for each month remaining.
So, if he's let go in April vs May, Clemson saves itself over $500k.
April 22 = $50k*48 months = $2.4M May 22 = $65k*47 months = $3.055M
Essentially, April is the best month, financially, to let him go. Obviously, you'll need to factor in recruiting, off-season workouts, availability of the next head coach, competitiveness to obtain next head coach, etc.