w:en:Template:Flagicon is a visible template; it inserts a small image of a flag. When editing https://en.wikipedia.org/wiki/Eder_Sánchez#Personal_bests (and others), it is displayed with both visible flag and the puzzle piece icon that signals the presence of an invisible template. The table doesn't adjust to accomodate this, so it's difficult to read inside the visual editor:

(When testing this outside a table, it first displayed the flag + puzzle piece icon, and then the puzzle piece disappeared.)