Rated 5 out of 5 stars

If you want to remove localized "Re:" alternatives (like the "AW:" in German), you should search the web for "mailnews.localizedRe". Thunderbird can detect localized variants natively, if correctly configured. This worked for me in Thunderbird 128.2. Please observe, that this applies only to new mails after you set it. Repairing a folder also activated the cleaning for me for the corresponding folder. Hope that helps!