Correct. Issuing all 40 million preferred shares at $25 after the authorization will bring in only $1 billion. Doing a SPO of 60 million shares at $28.50+ will bring in at least $1.7 billion, and can be repeated for 3 more quarters with even bigger share counts (doing a SPO of 19% of the float every quarter doubles the float every year).
No idea what they really intend to do with the preferred shares once they're authorized. Maybe they'll dump them all and make the SPO smaller, and maybe they'll dribble them out at the same rate as the SPO. Then they'd bring in $1.7+$1/4 ~ $2 billion this quarter.
And it's only been 2 months since the last SPO, and they did the preferred sale in the meantime, and may do some more of that. Relatively speaking, they are in good shape, and should be able to hold off on doing a SPO until after the ex-div in June.
I also think they should be lagging on MBS purchases to let rates rise, but then it's a question of what's worth more, the future value of future purchases at higher rates, or the interest that could be gained in the days or weeks between now and then by purchasing immediately, or the BV lost as rate rises erode value of those assets in that interval...