In recent news, it is the plan of the Nigerian government to redesign its currency notes. I don't know why such a project at this time is even mentioned, because other worst case scenarios that require redesign is left abandoned or nearly abandoned in total.
You have the explanation in the same article you've quoted:
“In recent years, the CBN has recorded significantly higher rates of counterfeiting especially at the higher denominations of N500 and N1,000 banknotes. Although global best practice is for central banks to redesign, produce and circulate new local legal tender every 5–8 years, the Naira has not been redesigned in the last 20 years.
It's nothing special, every country does so, even the Eurozone launched a new batch of banknotes designs in 2019, the US has changed the design of the $100 in 2010, and Britain just replaced two of their banknotes just to change them again after the death of the Queen.
Nothing to do with the economy, its standard procedure.