The bond between fluorine and chlorine is more likely to be covalent rather than ionic. Both fluorine and chlorine are nonmetals and belong to the same group in the periodic table (Group 17 or the halogens). When two nonmetals bond, they typically do so by sharing electrons, which results in a covalent bond.
Fluorine has a higher electronegativity (about 3.98) compared to chlorine (about 3.16), meaning that fluorine has a stronger tendency to attract electrons. However, the difference in electronegativity between the two elements (around 0.82) is not large enough to result in the complete transfer of electrons that characterizes ionic bonds. Instead, the electrons in a fluorine-chlorine bond are shared, leading to a covalent bond.
Additionally, since both elements are similar in their chemical nature and have high electronegativity values, the bond formed between them predominantly exhibits covalent characteristics, rather than the ionic characteristics associated with metals and nonmetals.