Nintendo is not going to do extensive QA testing for every single Switch game (especially not every third party shovelware game which might have had errors running on a regular Switch). I assume they ran every automated test they had handy and had someone spend X hours poking around the game to try to find issues.
The more interesting question would be how will games be fixed? Are they patching the game to fix the issue or are they patching the Switch 2 firmware to match Switch behavior? The more bugs they fix with the later approach the less important it is to exhaustively test every single game.
Nintendo is not going to do extensive QA testing for every single Switch game (especially not every third party shovelware game which might have had errors running on a regular Switch). I assume they ran every automated test they had handy and had someone spend X hours poking around the game to try to find issues.
The more interesting question would be how will games be fixed? Are they patching the game to fix the issue or are they patching the Switch 2 firmware to match Switch behavior? The more bugs they fix with the later approach the less important it is to exhaustively test every single game.
I expect they’ll patch both. Start with patches to the Switch and then, if the game can be patched, patch that.