The AI Z-depth module is very good in Vegas 21, but it is useless because the quality is not good. It calculates a different depth of field for two frames next to each other, but it is the same in the picture, only in the foreground a hand moves a little bit, but it does not shift the depth of field of the whole background. This is either a train problem or a programming problem. This should definitely be fixed because this plugin/fx cannot be used professionally. Davinchi also had this problem but there they solved it with the not so elegant solution of adding the sum of several frames together and the flicker disappears.  It's no good but it's better than flicker. Many people have struggled with this and there are working solutions on github like dynamic-video-depth which doesn't have this flicker. The problem there is that again we have to use an external program to make the depth even and not vibrate and then copy the good depth back into the program and use it. So dear Magix this vibration should be corrected somehow please.