Years ago I had a major depressive panic episode and deleted myself from the internet. I may never return to that comic, despite it being the most popular thing I ever made (nearly 600 watchers for that). At the time I did not know I was having a mental breakdown. As far as I was concerned it was "normal" and if you asked me why I did it I could not tell you. Not to suggest this is what your situation was. But please be gentle with yourself. Sometimes what stops creativity is more than just not having defined, shorter goals.
On the case that isn't the situation- People have mentioned creating short term goals to help keep motivation along- but please consider layered goals! Smaller goals within larger goals in case you find yourself with a bigger project. That is basically what I've done with my anthology project, Anamnesis.
Let's just say I have a LOT of parody isekai ideas. It made a lot of bloated scripts where I needed to let go of some ideas but I loved them so much I couldn't just let them go. So the answer should be, "let those ideas become there own stories". But then I'd find myself with over 30 stories that needed to be addressed! This is also not including all of the stories I want to tell that have nothing to do with isekai! So the next thing was to turn these all into short stories. Don't ask me why, but for some reason I decided they needed to be 20 pages or less. Since I was more in love with the de/reconstructive ideas, it made it a lot easier to design characters and setting to answer these questions my brain could not let go of. I started Anamnesis a year and a half ago and I am about to have 9 finished stories. Having completed works has helped me a lot in addressing my more serious, larger 200+ page scripts.
On the fear of keeping your audience waiting, find ways to be kind to yourself. You aren't being payed for this and you deserve breaks. I usually give myself breaks when I finish a chapter/story. This break can stretch for a week to an entire month. But don't feel like you can't take breaks at any other time as well! My mum and I have birthdays on the same week so I took that off even though my recent story was not finished.