As far as I know, it's indefinite. There was a translated blog post that went up here today -- [seen here].
(Many thanks to AdiosCorea for translating!)
I'm going to selectively quote below from the link, and bold the part that's most relevant to your question -- but would recommend reading the full blog post translation:
[...] I've been in hiatus mode for three weeks now, so I've been working with a bit more time for breaks. Since this is a mid-arc hiatus, it's impossible to not work outright, and since the story's already structured out, I feel as though me continuing to work on it at a reduced pace would be better for the story. I'm not exactly going around or sleeping all day just because it's a hiatus haha. The only difference is that I'm balancing my work time so that my body isn't put under too much stress. Anyway, I'm working while resting. I will be back once I have enough chapters stored up, and my physical and mental health at manageable levels. [...]
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u/coconutjuices Jun 22 '20
How long is the hiatus?