I think the major issue with Jumia is they have lost lots of ground to Konga. This, to me, is due to various reasons. Firstly, Jumia stopped advertising or drastically reduced their marketing budget a few years ago, when they became very popular. At that same time, Konga got funding and started massive marketing, which they continued till today. That struck Konga as the default place to shop on the Internet for most Nigerians.
Secondly, Jumia relies on their own stock, and the stock of a few other pre-vetted big merchants. Konga, on the other, welcomes everyone to sell with them, big players, tiny players, everyone in between. This ensured Konga always has stock beyond what they can stock themselves. There is a huge diversity on Konga, such that most people give up searching for a product if they can’t find it on Konga. Jumia, on the other hand, lacked many essential products, and lots of niche products. When they have it, the choice is severely limited, as typically it’s available from one merchant.
Konga ships stuff by themselves. They have a whole logistics company dedicated to shipping stuff. This makes it very easy for merchants to sell on their site. Their processes are also very automated (at least in Nigerian standard). This makes merchants more willing to sell on Konga, and of course the customers will go where the merchants are.
Jumia’s merchant website, kaymu, has always received much less attention than Jumia itself, and has made it difficult for it to be recognized by most people. Some people use kaymu only as a last option, and merchants don’t like it that much. It feels more like OLX. Konga doesn’t segregate their marketplace from their own shop, which makes it more trustworthy and more Amazon-ish while kaymu is more eBay-ish.
Finally, Jumia is everywhere at the same time. I’ve lost count of the number of Jumia owned websites and services. They’re basically dividing their labour, there is little focus. Not to talk of that they’re in so many other countries. You can only imagine the overhead costs involved in managing that many companies.