Yes, but it is not a direct subtraction.
The close of BIL on 3/28 was 91.80. Then a dividend was paid on 4/1 of .4047, so all the previous data has to be adjusted by a factor.
Here's how the factor is calculated.
C = close day before dividend is paid
D = dividend paid the next day
factor = (C - D) / C
This makes the factor .99559, so the close of 3/28 gets adjusted to 91.80 * .99559 = 91.395. And all other closes get adjusted also.
This matches Stock Charts numbers. If you want to see the unadjusted numbers I sure you know you can put in "_BIL".
I don't got back and adjust all the other prior months because all the numbers would just factored by the same number, so the ratio would not change.