That’s not quite the way it works.

Before Santos was expelled, the count was 222 R to 213 D. The “four-vote majority” really meant that Republicans could afford to lose no more than 4 votes on a measure: if five Republicans vote against it, the measure would fail by 1 vote, 217-218, assuming all members voted.

With Santos gone, the math is 221 to 213, as long as the seat remains vacant. The margin shrunk to 3, because a majority is needed to pass anything, and losing 4 ® votes now ties the vote at 217. When McCarthy leaves, with 2 vacant seats, it will be 220 to 213, but the margin remains 3, because losing 3 votes will still result in passage at 217-216.

Effectively, each vacant seat is like half a vote is lost. But then it’s more important to see how that seat is filled. I imagine McCarthy’s seat will remain Republican, but Santos ‘s seat on Long Island seems likely to flip, and that would go further to narrow the Republicans’ majority.