Someone's wild fantasy, presumably - possibly social media! Insane claim, and it's easily debunked using simple maths:
Qassams (the rockets used by Hamas) range between 35kg and 50kg in terms of mass (Source: Wikipedia).
Let's assume 50kg to be generous. 65k tonnes divided by 50kg would be 1.3 million rockets. Divided by 700 days, that'd be more than 1800 rockets a day ... which is just not happening.
No idea why people insist on making up the most easily debunked claims.