Not sure from that pic.
Almost looks like one of my thai pepper plants---except mine got cracked by the wind----bent over.
A little cheap tape cured my 3 bent stems in a couple days.
Yours almost looks like a lateral expansion split. Maybe someone else has experience in your type of problem.
For me it looks like a normal growth split. I have seen it on many of my plants before and were fine. From my experience it seems like the plant shed an outside layer around the base of the stem like a snake would shed its skin in order to grow. Your plant should be fine. Hopefully there will be others than can confirm this.