Hi
Thanks for contacting us. Note! Once you update to SP Page Builder 4.x from SP Page Builder v3.x, you can not roll back to SP Page Builder 3.x version. Make sure to test the page builder on a staging site and see if everything works as it should.
If I may add important tip.
If you made downgrade from SPPB 4.0 to SPPB 3.x - some pages that you edited using SPPB 4.0.x can be damaged becuase of different code structure between those. So I strongly recommend to recover database from the day before of SPPB 4.x installation. Or at least recover only table with prefix_sppagebuilder from that backup.
We cannot fix it, so this is the only way.
You can follow this link below:
https://www.joomshaper.com/forum/question/17702
-Regards.