There are multiple high oxidation state metal fluorides that can be synthesized and isolated in relatively large quantities as pure substances that have a higher electron affinity than Fluorine. The most oxidizing of these is Platinum hexafluoride whose electron affinity approaches 8 electron volts. To give you an idea of how insane that is, Fluorine’s electron affinity is slightly higher than 3 electron volts. i.e adding an electron to PtF6 liberates almost 3 times the energy that adding an electron to Fluorine does. It is such a strong oxidizer that it can tear an electron off Oxygen molecules to form PtF6 * O2. It was this observation that lead to the experiments that demonstrated the first nobel gas compounds. PtF6 reacts with Xenon to form a similar salt. This was the first time nobel gases were proven not to be universally inert.

Mixtures of Fluorine and lewis acids like Aluminum Fluoride, Antimony pentafluoride and the like can functionally act as far stromger oxidizing agents than Fluorine itself. These form superhalogen salts when they react with things or just destroy whatever it is that was unfortunate enough to be mixed with them.

PtF6 is not the molecule with the highest electron affinity that can exist. It is just the current record holder for the highest electron affinity of something we have been able to isolate as a pure substance. Hyperhalogens, which are essentially russian nesting dolls of oxidizing agents, can approach electron affinities of 10 electron volts. And while we cannot isolate these in their pure state, their extreme affinity for electrons can be used to stabilize otherwise unobtainable positively charged ions as salts.