During testing, I discovered issues with traffic statistics calculation.
The issue occurs exclusively with VLESS configuration when flow is disabled. Other protocols (tested with Trojan) do not exhibit this problem.

Test Case

Below are two screenshots demonstrating the issue. Both configurations are identical except for the flow setting.
Test procedure: After connecting via VLESS, download a 500 MB test file.
Expected statistics: user>>>downlink should show ~500MB.

Observed Behavior

As shown in screenshot №1, the statistics for user>>>4>>>traffic>>>downlink are inexplicably multiplied by 2 without any apparent reason.

This results in incorrect traffic accounting for users, showing double the actual usage when using VLESS without flow configuration.

• Affected versions: 25.12.8, 25.10.15 (other versions not tested)
• Protocol: VLESS without flow ("flow": "")
• Not affected: VLESS with flow (xtls-rprx-vision), Trojan

Test Case №1 – VLESS+Reality with flow: ""

Test Case №2 – VLESS+Reality with flow: "xtls-rprx-vision"

Xray Config

{
  "log": {
    "loglevel": "warning"
  },
  "inbounds": [
    {
      "tag": "VLESS_PRODUCTION",
      "port": 443,
      "listen": "0.0.0.0",
      "protocol": "vless",
      "settings": {
        "flow": "xtls-rprx-vision", // depends on test case
        "clients": [],
        "decryption": "none"
      },
      "sniffing": {
        "enabled": true,
        "destOverride": ["http","tls","quic"]
      },
      "streamSettings": {
        "network": "raw",
        "security": "reality",
        "realitySettings": {
          "show": false,
          "xver": 0,
          "target": "<omitted>:443",
          "shortIds": [""],
          "privateKey": "<omitted>",
          "serverNames": ["<omitted>"]
        }
      }
    }
  ],
  "outbounds": [
    {"tag": "DIRECT", "protocol": "freedom"},
    {"tag": "BLOCK", "protocol": "blackhole"}
  ],
  "routing": {"rules": []}
}