wrangler >=4.121.0 added `DO_NOT_TRACK`. Wrangler disables telemetry when DO_NOT_TRACK=1 is set, regardless of other telemetry settings. Older versions don't have it.

const { spawnSync } = require("child_process");
const fs = require("fs");
const path = require("path");
const dir = "/w/proj";
fs.rmSync(dir, { recursive: true, force: true });
fs.mkdirSync(dir, { recursive: true });
const home = fs.mkdtempSync("/tmp/home-");
function wrangler(args, extraEnv, dropEnv) {
  const env = Object.assign({}, process.env, { CI: "1", WRANGLER_SEND_METRICS: "false", NO_COLOR: "1", FORCE_COLOR: "0", HOME: home }, extraEnv || {});
  for (const k of dropEnv || []) delete env[k];
  const r = spawnSync(process.execPath, ["--no-warnings", "/w/node_modules/wrangler/wrangler-dist/cli.js", ...args], { cwd: dir, encoding: "utf8", timeout: 40000, env });
  const out = (String(r.stdout || "") + String(r.stderr || "")).replace(/\x1b\[[0-9;]*m/g, "");
  return { status: r.status, out };
}
function symptom(msg) { console.error("FAIL: " + msg); process.exit(1); }
function broken(msg, out) {
  console.error("ERROR: " + msg);
  if (out) console.error(out.slice(-2000));
  process.exit(2);
}
function write(name, content) {
  fs.writeFileSync(path.join(dir, name), typeof content === "string" ? content : JSON.stringify(content, null, 2));
}
const r = wrangler(["telemetry", "status"], { DO_NOT_TRACK: "1" }, ["WRANGLER_SEND_METRICS"]);
if (/Status:\s*Enabled/.test(r.out)) symptom("telemetry stays enabled with DO_NOT_TRACK=1");
if (r.status !== 0 || !/Status:\s*Disabled/.test(r.out)) broken("unexpected output from wrangler telemetry status", r.out);
console.log("OK: telemetry disabled by DO_NOT_TRACK=1");

const { spawnSync } = require("child_process");
const fs = require("fs");
const path = require("path");
const dir = "/w/proj";
fs.rmSync(dir, { recursive: true, force: true });
fs.mkdirSync(dir, { recursive: true });
const home = fs.mkdtempSync("/tmp/home-");
function wrangler(args, extraEnv, dropEnv) {
  const env = Object.assign({}, process.env, { CI: "1", WRANGLER_SEND_METRICS: "false", NO_COLOR: "1", FORCE_COLOR: "0", HOME: home }, extraEnv || {});
  for (const k of dropEnv || []) delete env[k];
  const r = spawnSync(process.execPath, ["--no-warnings", "/w/node_modules/wrangler/wrangler-dist/cli.js", ...args], { cwd: dir, encoding: "utf8", timeout: 40000, env });
  const out = (String(r.stdout || "") + String(r.stderr || "")).replace(/\x1b\[[0-9;]*m/g, "");
  return { status: r.status, out };
}
function symptom(msg) { console.error("FAIL: " + msg); process.exit(1); }
function broken(msg, out) {
  console.error("ERROR: " + msg);
  if (out) console.error(out.slice(-2000));
  process.exit(2);
}
function write(name, content) {
  fs.writeFileSync(path.join(dir, name), typeof content === "string" ? content : JSON.stringify(content, null, 2));
}
const r = wrangler(["telemetry", "status"], { DO_NOT_TRACK: "1" }, ["WRANGLER_SEND_METRICS"]);
if (/Status:\s*Enabled/.test(r.out)) symptom("telemetry stays enabled with DO_NOT_TRACK=1");
if (r.status !== 0 || !/Status:\s*Disabled/.test(r.out)) broken("unexpected output from wrangler telemetry status", r.out);
console.log("OK: telemetry disabled by DO_NOT_TRACK=1");