Hi Jamil,
they could be many... few of them could be
- link instability
- misconfiguration
- mistmatching limit of the max allowed number prefixes in the updates
- IGP issues that will propagate in their synchronization with BGP their flapping status
- too short timers (indeed BGP has been designed to have a slow convergence)
If it is a customer of yours flapping , you can use/configure dampening in your BGP process otherwise you can summarise your prefixes as workaround to this issue.
Alessio