Does Master Password Reprompt prevent decryption of vault items without MP?

When using Master Password Reprompt, does Bitwarden only decrypt the items when opening vault that don’t have MPR, or is this only a UI feature on the surface level?

I would like to have the cryptographic security of my master password, when using MPR, and didn’t find any sources or documentation, whether the MPR feature prevents only the amateur eye from seeing my password with my PIN code, or it really is a secure feature.

My main concern would be regarding the mobile app.

It is only a UI feature.

Master password re-prompt is not an encryption mechanism. This feature is an interface-only guardrail that a sophisticated user may find ways to work around. We recommend never leaving your vault unlocked when unattended or on a shared workstation.