I have received a feedback to change the following sentence:
Periodical reviews have been performed...
Periodical reviews are being performed...
Which of the sentences is correct, or are they both correct and expressing different meaning?
Both of these sentences are grammatically correct. The difference is the tense.
The first sentence is present perfect. It implies that periodical reviews were performed at an indefinite time in the past and probably this action is still going on now.
When you use present continuous, you are talking about the activities that are happening now and may continue in the future. So in your second sentence you are talking about the periodical reviews that are being performed at the moment and may continue to be done in the future.