As discussed in ietf-wg-ppm/draft-ietf-ppm-dap#729 (comment).

"Verify" is a natural term for VDAFs that use FLPs or arithmetic sketching to validate the output shares. It's not quite as good a fit for other MPC techniques we might want to fit into our framework, such as boolean-to-arithmetic sketching (as in Prio+). However, these remain hypothetical. In the meantime, "prepare" has caused us a ton of grief.