When charting, burnout is always a possibility. There are many ways people try to avoid it, but sometimes it's inevitable, this is why you see a lot of charters releasing packs then vanishing temporarily. There are a couple ways to mitigate the chance of experiencing burnout, though since burnout affects everyone differently, there is no guaranteed way to stop it from happening.
Firstly, try to limit how much you chart. I know it can be tempting when you're having fun to chart a tonne at once or marathon a chart to completion, but if you chart too much, you'll eventually get sick of it and the fun you once had becomes a chore. This is especially prevalant when you're hosting a pack. Speaking as someone who's been behind the scenes for a number of major Etterna packs, I can tell you that a lot of charters lose steam long before the pack is finished, but feel the need to keep chugging along to finish the pack, which completely kills their motivation and causes burnout.
The second way to avoid it, and the way I avoid it myself, is to make sure that when you're in the editor, you're having fun for at least the majority of the charts you make. View charting as a hobby you enjoy, rather than a chore to get charts you want to play. This can be done by doing what experienced charters refer to as "funstep". That is the act of charting something occasionally that is entirely, 100%, for fun. Placing down funny/entertaining patterns that you enjoy or make you giggle that you'd never normally place under any circumstances, or just messing about in editor with no intent to finish a chart. This freedom can help you mitigate potential burnout.
These two actions can help mitigate burnout quite significantly, but ultimately only you know what can cause burnout, so while these might be useful, you should always focus on doing what you think works best for you.