Product and version
FileMaker Pro Advanced 18.104.22.168
OS and version
Windows 10 Pro
FileMaker adds all fields of a table to the current layout if you change the definition of a field of this table. This does not only happen for newly created tables (where this behavior is expected) but also for tables that are there for a long time. Even fields that are already on the layout will be added again. So far this happend about 15-20 x im my current solution over the past few weeks but I cannot see a pattern when it happens and when not.