"Felon" is usually reserved for reserved for people who have been both convicted of a felony and sentenced, which e.g. does not currently apply for Trump, though his sentencing is currently set for ~11 July.

Potential arb here against the general election markets: if you assume Trump will be "a felon" by the 2024 election's completion, P(felon becomes POTUS) should be strictly-if-marginally greater than P(Trump becomes POTUS), and if you assume the opposite the odds should be extremely low. As of writing P(Trump becomes POTUS) is hovering around 53% on the main appropriate market.