That can also happen to plastic carboys when you fill them with hot wort because you forgot to turn on the water to your counter flow chiller.
Don't do that.
Filled the carboy with oxi to soak. Moved to garage to make room for guests and forgot about it over the holidays with nightly lows in the single digits. Don't do that.
Patersbeir are basically the lower abv beers that the monks drink on a day to day basis. Stronger beers are reserved for feast days. Also called refectory beers.