Indeed, if you are only showing part of a document, this is highly likely a problem with your settings. Maybe some transformational show rule somewhere.
I can reproduce what @Y.D.X posted in Spacing with text in equations with a single CJK charater - #4 by Y.D.X. If there are spaces in the source, it will be reflected in the output.
My guess is that some math-related package is used that modifies math.equation, like quick-maths – Typst Universe or something.
The guidelines say that you should post minimal code, and so far it renders correctly for at least 2 of 3. How to post in the Questions category
Also, https://sscce.org can be useful in the long run.