At one point, Democrats had to win 8 out of 9 toss-ups. I think that would be .5 raised to the 8th power or .00390625 or less than .4%. That’s with a fair coin.
If Republicans lose the House, the coin was not fair.
If they lose the house it would be certainly an anomaly based on historic patterns.
I should probably dive into the 4 elections where the exception case happened and see if there is there was a pattern to them.