NIGERIA is largely dependent on crude oil for foreign exchange, so when crude oil prices or volume drops, the exchange rate falls.

Nigeria depends on imported petroleum products because we do not yet have a functioning Refinery as a local refinery which is being built will start functioning, Next year March,2023.
So we have to import our crude oil to foreign countries for the Refining process

The cost of importing this refined petroleum products exceeded the Petroleum exports by 43.56 Billion dollars in 2020.

Also Nigeria's oil production has dropped to 1.24 million Barrels per day in March, The lowest so far in 2022.

So this has really affected the economy as it has led to Fuel scarcity and a great hike in price of Petroleum

The 18.61% rate is as at June,2022. As we are still dealing with the effects presently

It's affecting everyone in General as a lot of Naira is chasing very few Dollars.

I hope this was explanatory enough and this answers your Question