Here LO 26.2.6.3, Fedora 44 (Linux)
Even after deleting all your sections, the behaviour persists: the column heading reappears after deletion but if I add, then remove blank lines before the table, the column heading disappears again. So, the bug does not seem to be related to sections.
I suspected something about fonts (metrics, perhaps). Roboto is not installed on my system, so I replaced it, but it is independent from font choice.
Remark: your sections do not make sense. Creating 1-column sections without other properties like note management bring nothing to the document. It is rather detrimental to stability and performance.
In addition, you have conditionally hidden some sections but the conditions are faulty, always resulting in FALSE, making the section always visible.
Try to simplify your document structure and avoid direct formatting, use styles instead.