Catalyzes the reversible decarboxylation of aromatic carboxylic acids like ferulic acid, p-coumaric acid or cinnamic acid, producing the corresponding vinyl derivatives 4-vinylphenol, 4-vinylguaiacol, and styrene, respectively, which play the role of aroma metabolites (PubMed:20471595, PubMed:25647642). Not essential for ubiquinone synthesis (PubMed:20471595). (E)-4-coumarate + H(+) = 4-hydroxystyrene + CO2 (E)-cinnamate + H(+) = CO2 + styrene (E)-ferulate + H(+) = 2-methoxy-4-vinylphenol + CO2 Binds 1 prenylated FMN (prenyl-FMN) per subunit. kcat is 3.8 sec(-1) with ferulic acid as substrate, 1.5 sec(-1) with p-coumaric acid as substrate and 4.6 sec(-1) with cinnamic acid as substrate. Optimum pH is 7-8. Homodimer (PubMed:25862228). May form higher order oligomers (PubMed:25647642). The measured mass includes the mass of an N-terminal hexahistidine tag, expressed in E.coli. Present with 861 molecules/cell in log phase SD medium. Belongs to the UbiD family. UbiD-like/FDC subfamily.