A simple script to do cargo tree -i, use that instead. I wrote this since I didn't find that.

cargo-why.py

import sys

try:
    import tomllib
except ImportError as e:
    print(e, "require python 3.11, exit", file=sys.stderr)
    exit()

from pathlib import Path
from typing import Any, Dict, List

if len(sys.argv) == 1:
    print(
        f"""
usage:
  python {Path(__file__).name} your_proj target_deps
""",
        file=sys.stderr,
    )
    exit()

dic: Dict[str, List[str]] = {}
project = sys.argv[1]
to_be_find = sys.argv[2]
roots: List[str] = tomllib.load(Path(project, "Cargo.toml").open("rb"))[
    "dependencies"
].keys()

package: List[Dict[str, Any]] = tomllib.load(Path(project, "Cargo.lock").open("rb"))[
    "package"
]
for f in package:
    dic[f["name"]] = f.get("dependencies", [])


def dfs(r: str, arr: List[str]):
    if r.startswith(to_be_find):
        print(*[*arr, r], sep=" -> ")
        return
    if " " in r:  # something like "aa 1.0"
        rr = r.split()[0]
    else:
        rr = r
    for i in dic[rr]:
        dfs(i, [*arr, r])


[dfs(x, []) for x in roots]