I used amplify effect and the error says that the settings could not be used
Yes, it’s a bug.
I first noticed it when cancelling the effect (clicking the [X] close button), but on testing again today it occurred when applying the effect.
From my testing, it appears to only happen on first use of the effect. Once the Amplify effect has been applied, it seems to work correctly for the rest of the session.
The bug is logged here: https://github.com/audacity/audacity/issues/3682