The JAMB has disclosed that the results of 2020 JAMB candidates that have already been released may likely be withdrawn depending on the outcome of the review of the CCTV footage and other technical gadgets installed at the various CBT centres used for the exam nationwide.
This means that even though you have already seen your result, it may still be withdrawn by JAMB if it is discovered at any time through the CCTV footage that you were involved in any form of examination malpractice.
JAMB has already released the names of candidates who so far have been confirmed to have involved in various forms of malpractice. You can check the names of candidates via this link: JAMB 2020: Names Of Candidates Caught In Malpractice
If you were involved in examination by proxy, attempt to cheat, forceful entrance, tampering with examination documents, smuggling of mobile phones into the examination halls etc, there is a high possibility that your result will be withdrawn if it has already been released.
Also, for candidates who have been unable to see their JAMB results, it could be that your results are still under review. Once JAMB is able to establish that you were not involved in any form of malpractice, your result will surely be released. You only need to exercise patience.