In general, the mechanisms promoting photoacidity are related to the reorganization of charge distributions upon excitation in the nearby regions of the proton donating group, as it has been proposed for the case of naphthols. The delocalization of negative charges in the conjugated base can also be a driving force to photoacidic behavior. In addition, there can be a combination of effects from changes in the charge density and electrical dipole moments upon excitation in both proton donating and accepting groups, as recently demonstrated for APTS through experimental picosecond nitrogen K-edge spectroscopy. Another important interpretation of the origins of photoacidity is given in terms of excited state antiaromaticity (ESAA) relief. In the mid-60s the aromaticity and antiaromaticity concepts were employed by Dewar and Zimmerman to describe transition states of allowed and forbidden pericyclic reactions, both thermal and photochemical ones. Then, in the early 70s Baird used perturbation molecular orbital theory to qualitatively derive the rules for T1 state aromaticity and antiaromaticity, and they have been found in computations to be valid also for the S1 states. In short, Baird's rule tells that the electron counts for aromaticity and antiaromaticity are opposite to those of the S0 state, i.e. systems with 4n+2 π-electrons are antiaromatic in their lowest ππ* triplet and singlet excited states. Excited-state aromaticity and antiaromaticity have been used to explain several photophysical and photochemical processes, including photoacidity. For instance, the different 𝛥𝑝𝐾 𝑎 values of photoacids derived from naphthalenes could be correlated to their degree of ESAA relief when going from the acid to the conjugate base. In a similar way, the evaluation of nucleus-independent chemical shifts (NICS) values along proton transfers in DNA base pairs were shown to be driven by (anti)aromaticity changes, from aromatic character in the S0 state to antiaromatic in the excited state. In this work we present a case to which none of the aforementioned mechanisms of photoacidity could be applied as a stand-alone explanation. We design the organic dye 5-[4-