EDIT: SOLVED.
Changed my font size from 140% to 100% and it worked normally.
If you can see, the mathjax appears conjusted/without space and the EXACT card appears/renders normally in pc anki. Any solutions?
See Mathjax looks "bunched up".
I don’t think the OP of that topic did what David asked for, so you should do it.
Edit: sorry, here’s the issue MathJax √ radical bar has vertical+horizontal gap from √ glyph (AnkiDroid only; MathJax 3 CHTML) · Issue #20776 · ankidroid/Anki-Android · GitHub.
I think a temporary fix for you might be to change your phone’s font size.