There is no joy in going to a job you hate. Well, OP, if you have spoken to your line manager about what makes you unhappy and they seem adamant about helping you fix aspects of the work that you do not enjoy to make it better, I would say that you should consider an alternative, which may be a new job that fits in with your interests and skills. or even switching career paths totally. Also, remember that we live in a time where you need multiple streams of incomes. So despite your side hustle paying more, you need more streams even if you decide to look for another job.