Run the snippet https://snippet.webix.com/u1swvzqz in Safari 14.0.2 under Big Sur (on an M1 Mac, if that matters).
When you click on a cell to edit, hit one of the arrow keys, then hit esc, the non-locked part of the datatable to the right gets out of alignment with the locked columns on the left, and shifts horizontally as well (often leaving a blank space).
This works fine with Firefox and Chrome. Only Safari 14 seems to have this bug. Earlier versions of Safari seem to work as well, I believe. Perhaps this is a Safari problem and not a problem with Webix. But it’s worth investigating.