Can you screenshot it and upload an example here.
Put the phone in Safe Mode which will turn off all the downloaded apps and leaves the stock ones alone which can then help you determine if its a rogue app causing this.
Daily Driver > Samsung Galaxy s²² Ultra 256Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help.
I would recommend "nice catch" by Samsung. This app allows recording the history of features on your phone. One of these is toast history and this will tell you if a system app or another app is causing the toast message your experiencing.
Hope this helps.