Regex filter incorrectly matches

[deniswassmann-alephalpha]

Describe the bug
A regex pipeline stage |~ "(?i)/\\$\\{\\#" somehow matches a multiline log entry with the content of

ansible-ansible.legacy.command Invoked with _raw_params=#!/bin/sh
set -u

# This script is downloading the OS-specific JFrog CLI binary with the name - 'jf', and adds it to PATH

CLI_OS="na"
CLI_MAJOR_VER="v2-jf"
VERSION="[RELEASE]"
FILE_NAME="jf"

if [ $# -eq 1 ]; then
    VERSION=$1
    echo "Downloading version $VERSION of JFrog CLI..."
else
    echo "Downloading the latest version of JFrog CLI..."
fi
echo ""

if uname -s | grep -q -E -i "(cygwin|mingw|msys|windows)"; then
    CLI_OS="windows"
    ARCH="amd64"
    FILE_NAME="${FILE_NAME}.exe"
elif uname -s | grep -q -i "darwin"; then
    CLI_OS="mac"
    if [ "$(uname -m)" = "arm64" ]; then
      ARCH="arm64"
    else
      ARCH="386"
    fi
else
    CLI_OS="linux"
    MACHINE_TYPE="$(uname -m)"
    case $MACHINE_TYPE in
        i386 | i486 | i586 | i686 | i786 | x86)
            ARCH="386"
            ;;
        amd64 | x86_64 | x64)
            ARCH="amd64"
            ;;
        arm | armv7l)
            ARCH="arm"
            ;;
        aarch64)
            ARCH="arm64"
            ;;
        s390x)
            ARCH="s390x"
            ;;
        ppc64)
           ARCH="ppc64"
           ;;
        ppc64le)
           ARCH="ppc64le"
           ;;
        *)
            echo "Unknown machine type: $MACHINE_TYPE"
            exit 1
            ;;
    esac
fi

URL="https://releases.jfrog.io/artifactory/jfrog-cli/${CLI_MAJOR_VER}/${VERSION}/jfrog-cli-${CLI_OS}-${ARCH}/${FILE_NAME}"
echo "Downloading from: $URL"
curl -XGET "$URL" -L -k -g > $FILE_NAME
chmod +x $FILE_NAME

# Move executable to a destination in path.
# Order is by destination priority.
set -- "/usr/local/bin" "/usr/bin" "/opt/bin"
while [ -n "$1" ]; do
    # Check if destination is in path.
    if echo "$PATH"|grep "$1" -> /dev/null ; then
        if mv $FILE_NAME "$1" ; then
            echo ""
            echo "The $FILE_NAME executable was installed in $1"
            jf intro
            exit 0
        else
            echo ""
            echo "We'd like to install the JFrog CLI executable in $1. Please approve this installation by entering your password."
            if sudo mv $FILE_NAME "$1" ; then
                echo ""
                echo "The $FILE_NAME executable was installed in $1"
                jf intro
                exit 0
            fi
        fi
    fi
    shift
done

echo "could not find supported destination path in \$PATH"
exit 1
 _uses_shell=True expand_argument_vars=True stdin_add_newline=True strip_empty_ends=True argv=None chdir=None executable=None creates=None removes=None stdin=None

To Reproduce
Steps to reproduce the behavior:

1. Started Loki version 3.1.1 (branch: release-3.1.x, revision: 89fe788)
2. Started Promtail (SHA or version) to tail '...' any agent will do. we are using alloy
3. query

   {whatever_label_selector="you_need_to_fetch_said_log_line"} |~ `(?i)/\$\{\#`
   

Expected behavior
The query should not return the aforementioned log line because the regex does not match the content. Searching for the only text matched by the regex (/${#) using the query {some="selector"} |= "/${#" will not return the log line in question, as expected.

Environment:

• Infrastructure: bare-metal
• Deployment tool: loki (and grafana) are installed via official packages and running as systemd services

Screenshots, Promtail config, or terminal output
none. i can provide additional information if necessary