MacBook Pro screen is flickering

Usually that will be a hardware issue of some sort. Have Apple or an Apple Authorized Service Provider examine the laptop to assess the issue and possibly provide a repair estimate for a repair.

This is something that will need to be seen in order to assess ... sometimes it may be caused by a software issue as well, but that can be hard to distinguish unless the issue only happens when using one particular app.

If you had any repairs performed, then you have a 90 day part or repair warranty depending on how the laptop was repaired. You definitely want to take advantage of this to address this issue.

You can try connecting an external display and enable mirroring to see if the flickering also occurs on the external display. If the flickering only occurs on the laptop's built-in display, then it means there is a hardware issue with the laptop's built-in Display Assembly.

If you were already using an external display, then disconnect the external display in case it is causing the problem. In fact disconnect all external devices in case any one of them is causing a problem.

If the flickering is caused by software or the GPU or Logic Board, then it will be difficult to figure out which is the cause which is why you may need to have Apple or an AASP examine the laptop to try to determine the source of the problem.