That lighter grey text is intentional — not a glitch.
What it means: Grey rows are expenses that have already been added to a report (via Create Report). When you create a report, ExpenseBot greys those rows and stamps the date in the Submit Date column (column W, over on the far right). The grey is a visual cue so you can tell at a glance what's already been put in a report versus what's still outstanding and available to report.
Is it safe to change the colour? Yes — editing the text colour won't break anything. Just know that ExpenseBot may re-apply the grey the next time reports are generated, and those rows stay marked as already-reported regardless of what colour you set. The Submit Date in column W is the reliable record of what's been reported.