But if these are very old video cards, such as RX 480, then mining on them is unprofitable.
Yeah true. If you have newer cards your revenue is the same like 2019 with RX4x0/5x0. At this time the reward per card was around $0,20 before power.
but at the moment you can mine Dynex with the good old RX4x0/5x0 cards, give an return of up to $0,30 the last days, but decrease at the moment.
Sometimes it pops something up and i turn on the last 2 RX Rigs

The real profit of the Dynex coin is 20-25% lower than in calculators. Therefore, you will not like real profit on old video cards