[Laurence Thompson]

Brian,
This could be a few different issues, but I would like to propose one possible issue that may be causing this:

The first monitor you had will have a different colour profile compared to the second and third monitor. These new monitors may display problems in compression of the footage that may not see on the first monitor. For example the new monitors may be showing more detail in the blacks and therefore you can see compression blocks in the black areas on the new monitors that you may not have seen prior.

It is possible the new footage doesn’t have this problem as it was lit differently, had less movement in the shot or simply that there is little detail in the shot, so less compression is required.

Maybe a screenshot to show what the artifacts look like might help?

Cheers,
Harry

https://www.pinefreshmedia.com.au/
Melbourne Video Production Services