I’m not sure how to word this.
Print shifting is a common issue and can be many many many things. Telling us it moved doesn’t say much. Pictures with every post help so much. If it slipped leave it attached so we know what direction it slipped in, show the whole machine in the pic. I know this is not your case but yesterday while I was watching the printers having my coffee, there was a quick brown out out. all 6 printers stopped for about 5 seconds and then actually kept printing, one slipped in the y directions by about 2mm the rest were fine. It literally can be anything. I had one slip every time my washing machine turned on in a previous apartment because of the power dip.
Did it move on the same axis every single time?
Did it move at the same exact height every time?
Have you changed the size of your machine yet?
What are all of your speeds in your slicer?
Have you tried another slicer?
Do you models have overhangs that usually are the culprit? If your test prints printed fine it sounds like a model issue. Some things do not print well. TRy printing some mpcnc parts, we all know they print well.
Did you change any of the drivers voltages at all? Do you have a cooling fan on them?
A 30×30 build isn’t all that big, 2 of mine are that exact size, with 4 and 6″ z axis.
Using the wiring harness?
Using the 525 parts or previous?