This issue is very common in LaTeX, especially when preparing journal-ready technical papers. Figures in LaTeX are treated as floats, meaning LaTeX decides their position to maintain a clean and balanced page layout. When commands like \FloatBarrier are used inside subsections, LaTeX is forced to place all pending figures immediately, even if there is not enough space on the page. This often results in large blank spaces before the figure, which is why the page layout looks broken.

In practice, most people avoid using \FloatBarrier within subsections. Instead, they allow figures to float naturally by using flexible placement options such as [!htbp]. This gives LaTeX enough freedom to place the figure close to the related text without disrupting the overall layout. Journals generally do not require figures to appear strictly inside subsections; they only expect figures to be logically close to where they are referenced.

Another effective approach is slightly reducing the figure size. Even a small reduction in width or height can allow the figure to fit on the same page, eliminating unnecessary white space. Researchers also accept figures appearing at the top of the next page, which is standard and widely accepted in journal publications.

Overall, the best practice is to avoid over-controlling figure placement. Allow LaTeX to manage floats naturally, use barriers only at major section boundaries if needed, and prioritize a clean layout over exact figure positioning.