The rulebook mentions that after an outburst you lose strife, but I have read the section several times and can't find out how much strife you lose. Did I miss it?

Quote

[P. 17] In addition to removal of strife as a result of an outburst...

Don't know if you found the answer or not, but your strife should fall down to half your composure after an outburst. For some reason, they mention it at the ends of the paragraphs detailing the types of outbursts.

it only says it in the example outbursts (P17)

"At the end of the scene, the character removes strife until
their strife is equal to half their composure"

That sentence is a consistent mention of strife after outburst removal for the five examples given.