Do you have the "imtranslator" plugin installed on your browser? This translator can automatically add HTML code to your signature.
For example :
Believe us, this behavior is quite involuntary.
The suggested solution is to deactivate this plugin from your browser, delete the signature "affected" by this behavior and create a new one.
Once you've made these changes, you can reactivate your translator.
#IMTranslator #compatibility #issue