By using the Twitter \ac{API}, Hybrid \ac{OSN} is very strongly bound to Twitter. Restrictions to the \ac{API} would have a significant impact on the Hybrid \ac{OSN} client. In order to link content and actions to users and tweets, a referencing of the respective id is necessary. If these ids disappear from the system because tweets are deleted or users leave the platform, the private data can no longer be assigned and lose their significance.

For the hybrid client to achieve the best possible result, a copy of all the functionalities of the original \ac{OSN} must be implemented decentrally. In particular, the problem of finding specific content has to be solved. GUN fulfills this requirement only partly since only user ids can be looked up. Besides, GUN needs a relay server to connect peers. This server represents an unwanted single point of failure.

Private tweets are loaded into the user's timeline by active pulling. With the user ids of the friendly accounts, their private tweets are looked up. Since the data structure in GUN is optimized for searching by user ids, searching for a keyword or hashtag is not possible in an elegant way. To perform such a search, first, all hashes need to be extracted from GUN and downloaded form IPFS. Second, all this data needs to be decrypted and searched locally for the given keyword. For a small amount of data, this is maybe practical. However, it does not scale and is, therefore, no permanent option.

Since there is currently no pushing from the back end or periodically updating, push notifications are missing. The user always has to open the app and check for updates himself. If someone else, who is no friend of the user, mentions the user in a private tweet, there is no possibility he will ever notice.

The data stored in \ac{IPFS} cannot be deleted and subsequently edited. Also in the Hybrid \ac{OSN} app, the deletion of single private tweets is not implemented at the moment. The users of Peepeth strongly criticized this circumstance \cite{peepeth2018free}, hence this is also a limitation for the Hybrid \ac{OSN} users. While tweets cannot be edited afterward, they can be deleted so that there is a difference to the hybrid implementation.

Data exchange via GUN only works if peers are online at the same time. As Hybrid \ac{OSN} is an application for a smartphone, a permanent connection is not guaranteed. Furthermore, the connection is not maintained in the background, but only when actively using the application. Especially in the initial phase with few users, this is a substantial limitation. Super peers could solve this problem, but this requires the installation of more servers.