With the effect of visa restriction on Nigerians in UAE there are a lot of speculations on the reason for the visa ban. Just yesterday, the Nigeria Government place a ban on Emirates airline, https://africonet.com/fg-bans-emirates-airlines-from-operating-in-nigeria/
This was seen as reprisal by political analyst, on visa ban on its passport holder by UAE. Recall that the Nigerian government has earlier said that there will be restriction on countries that are restricting its citizens and passport holders.
Many see the actions by Nigeria government as a welcome development as there will be a level playing field for dialog. Both countries are yet to give official statement on both the visa restriction on Nigerians and the ban on both Etihad and Emirates airline from operating in Nigeria
Unconfirmed information from screenshot from This day, portray that both the visa restriction on Nigerians and the ban on Emirates airline will likely be lifted before Monday 21st of September as seen in the screen shot below.