Ok, I've identified the root of my confusion here. Mochi has two FAQs:

https://mochi.cards/faq.html Mochi uses SM-2 without EF adjustment and without resetting intervals. This is outdated.

https://mochi.cards/docs/faq/ says Mochi multiplies by a number >1 on recall and by a number in [0,1] on forgetting. This FAQ is linked from the front page and seems to be the correct one.

And, indeed, checking the review settings for my deck shows the multiplier settings.