"Berkshire has about $152bn in cash, and says they won’t go below $30bn."

while he said $30b in the past, it is likely more like $70- $100b given the growth of the firm

This is in every quarterly report:

Berkshire Hathaway: PDF document
Page 52:
"The program does not specify a maximum number of shares to be repurchased or obligate Berkshire to repurchase any specific
dollar amount or number of Class A or Class B shares and there is no expiration date to the repurchase program. Berkshire will
not repurchase its common stock if the repurchases reduce the total value of Berkshire’s consolidated cash, cash equivalents and
U.S. Treasury Bills holdings to less than $30 billion."

But in practice they don't take cash + fixed income far below float amount, and even then not for very long.
That's based on observations since 2010.

Cash+Fixed/Float
2010 to 2023
105%
92%
100%
94%
101%
99%
102%
109%
105%
111%
113%
109%
92%
104%