Your table field(s) could be formatted for one case or the other (@> or @<) OR your form controls are similarly formatted OR your data is actually entered that way. In the latter case, your data might be one case or the other but the field(s) have a format which alters what you see. You have to examine the field and control formats to see if that is over-riding (altering) what the actual data is.
If your data is actually mixed format and you want to change the data (e.g. dog > DOG) you can run an update query against those fields.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.