If you are trekking in Bali, you should consider vaccination against hepatitis A and typhoid, as these diseases occur in Indonesia. Other vaccines which might be considered include vaccination against Japanese encephalitis, hepatitis B and rabies.
It is also important to ensure that your routine and COVID-19 vaccinations are up-to-date including measles, mumps, rubella, diphtheria, tetanus, pertussis (whooping cough), hepatitis B, polio, influenza and pneumococcal disease.