dis ‧ ad ‧ van ‧ ta ‧ geous /ˌdɪsædvənˈteɪdʒəs, -væn-/ BrE AmE adjective [+ to/for] formal
[ Word Family: noun : ↑ advantage ≠ ↑ disadvantage , the disadvantaged; adjective : ↑ advantageous ≠ ↑ disadvantageous , ↑ advantaged ≠ ↑ disadvantaged ; verb : ↑ disadvantage ; adverb : ↑ advantageously ≠ ↑ disadvantageously ]
unfavourable and likely to cause problems for you OPP advantageous
—disadvantageously adverb