We've updated the Online Generator and Meta Box Builder, used the PHP Encoder to encode the Tonal Language (Pestañas, Vehículo, Tiếng Việt) and optimize the generated PHP code. It's not an error PHP code so don't worry about that.
If you use the Builder to generate the code then paste the code to the file functions.php, please re-type the name of the field. I'm going to discuss with the developer team to research and cover this case. Thank you.