EDIT: in some (or perhaps many) countries this is explicitly forbidden in many cases.
One explicit legal norm in Germany: § 331 StPO: Verbot der Verschlechterung (Penal rules of procedure: prohibition of pejoration)
Switzerland also knows the prohibition of reformatio in peius in many cases but it stems from the legal maxime that in some trial types the judge never goes beyond what the party has requested, but this is a double-edged sword: on one hand you are protected from reformatio in peius but on the other hand you miss out on opportunities you did not think about and therefore did not request. Sometimes the judge even maliciously adds to the decision that there was a right to something but it won't be granted because it was not requested.
[0]: https://en.wikipedia.org/wiki/Reformatio_in_peius
EDIT: in some (or perhaps many) countries this is explicitly forbidden in many cases.
One explicit legal norm in Germany: § 331 StPO: Verbot der Verschlechterung (Penal rules of procedure: prohibition of pejoration)
Switzerland also knows the prohibition of reformatio in peius in many cases but it stems from the legal maxime that in some trial types the judge never goes beyond what the party has requested, but this is a double-edged sword: on one hand you are protected from reformatio in peius but on the other hand you miss out on opportunities you did not think about and therefore did not request. Sometimes the judge even maliciously adds to the decision that there was a right to something but it won't be granted because it was not requested.