Why are control characters added to test.md?

I am using a dialog in order to modify a single value into a file:

#!/usr/bin/env bash

prompt_and_save() {
    local file=$1
    local message=$2
    local value=""

    # Check if file exists and read value
    if [ -f "$file" ]; then
        value=$(cat "$file")
    fi

    # Prompt user with dialog
    value=$(dialog --inputbox "$message" 8 50 "$value" 3>&1 1>&2 2>&3)

    # Save the value if not empty
    if [ ! -z "$value" ]; then
        echo "$value" > "$file"
    fi

    clear

    # Return the value
    echo "$value"
}

UPSTREAM_VERSION=$(prompt_and_save "VERSION" "Bump the version (or keep it the same)")
clear
NEW_ENTRY="# Version $UPSTREAM_VERSION $DATE"
RELEASE_NOTES=$(cat RELEASE_NOTES)

echo -e "$NEW_ENTRY\n${RELEASE_NOTES}" > test.md

But running this script I get these values in test.md:

# Version ^[[H^[[2J^[[3J0.2.0 
1. Split codebase into multiple files.
2. Use a seperate version file and define built version upon compile.
4. [BUGFIX] If input file is same as output file copy input file into a temporary one.
5. Improved Documentation
6. [BUGFIX] Out of bounds argument parsing
7. [BUGFIX] Values should not be an Argument

How can I remove any control characters from UPSTREAM_VERSION before echo it into the file?