Shame on me for using a "special" read-only account for data comparison, but I'm not a fan of the Sync behavior change that I see in 13.1 vs. 12.12. A big fat button to magically change the target vs. a little drop down arrow on the side of the same button to do the only action that I would ever consider doing, send to editor, is just a bad design change in my opinion. 12.12 offered 3 separate but equally sized button options along with more flexibility with the Delete/Insert/Update options. Typically I Insert only the missing stuff and occasionally update, but only after manual reviews and edits.
I switched from 12.12 to 13.1 mid-way in comparing ~400 incoming tables with the consolidated target (think verifying/merging common client reference data when consolidating client databases). Sheer panic hit when I realized what the new Sync button had done. I had done no review of triggers or anything. Boom it was done. No script. Just done. Fortunately there were no triggers or downstream impact and I had another recent copy of the original target data set to repair the deed.
For me a real time sync is almost never used. Having it as the default is a huge risk and now I can only safely perform the work with a real read-only account.
Please reconsider this design change.