This is actually a rethorical question.
I know that the purpose of backlog refinement is to take upcoming PBIs, break them down into smaller items and have discussions with the development team to better understand the PBI before committing it to the sprint.
However, the very fact you are having these discussions and breakdown, does that mean you are in fact doing the bulk of the analysis for those PBIs prior to committing to a sprint and therefore, when committing to the sprint isn't most of the analysis work done?