In the vector options (both in the main settings and the schedule settings), ticking meaning -> japanese doesn't make 'prevent newly added vectors' appear.
If you toggle meaning -> japanese on like in screenshot1, the "prevent newly added..." won't show up. If you select meaning -> kanji/kana then 'prevent newly added' will appear as in screenshot2. You can then toggle the other one and also meaning -> japanese and 'prevent newly added' will remain visible (screenshot3).
Why this is a problem: If I check meaning > japanese as in the first screenshot, it is unclear whether it's preventing newly added vectors from flooding or not (I think it does). I believe anti-flood is irreversible, so if the user didn't want that and it treats it as toggled on, there would be no way to fix it. Right now I have to make sure I toggle meaning -> japanese 'correctly' to make sure anti-flood isn't triggered.
Do you mind trying it now to see if you can still reproduce the issue?
The exact issue I posted about seems fixed now, but there is still a related bug there. If you start with Japanese > Meaning ticked, then tick Meaning > Japanese (as in screenshot1), but then untick Japanese > Meaning, it will hide 'prevent newly added vectors' even though a new vector is ticked.