Autocomplete's listbox Paper defaults to elevation 1, while Select/Menu's Popover defaults to elevation 8 — inconsistent shadow between components with the same UI role

Steps to reproduce

1. Open this link to live example: https://stackblitz.com/edit/gn7fmuvs?file=src%2FDemo.tsx
2. Compare the box-shadow of the open Select's Menu Paper vs. the open Autocomplete's listbox Paper

Current behavior

The Select's Menu Paper defaults to `elevation={8}

The Autocomplete's listbox Paper renders with no explicit elevation passed in paperProps, so it falls back to Paper's own default of elevation={1}:

Two components that serve the same UI purpose — a floating list of selectable options anchored to a field — render with visibly different shadow depth by default.

Expected behavior

Either:

• Autocomplete's listbox Paper should default to the same elevation as Select/Menu's Popover (8), since both are "floating option list" surfaces anchored to a field
  and are commonly used interchangeably in the same UI (e.g. a filter bar mixing plain Selects and Autocompletes), or
• If the difference is intentional (e.g. Autocomplete is meant to read as a lighter-weight surface), this should be documented, so it's clear the mismatch has to be
  fixed manually via slotProps={{ paper: { elevation: 8 } }} when visual parity with Select is wanted.

Context

No response

Your environment

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Start with the linked StackBlitz reproduction in src/Demo.tsx and compare the Autocomplete listbox Paper with the Select/Menu Popover. Inspect the existing Paper defaults and slotProps API, then confirm the intended relationship between their elevations. Done means the default behavior is consistent or the intentional difference is documented, with the reproduction reflecting that decision.