If you can't be "arsed" to give your best that's a different issue and it sometimes is a simple case of burnout. This happens when you give a job too much over a long period of time.
As for your current role, I see issue immediately. Estimates are nothing more than estimates but in your case they seem to be deadlines. It should be a simple case of having a human discussion ... it takes longer because of an issue I have, not seen in the estimation stage. You can't basically foresee everything and that's normal and expected. Software development is not a factory setting but a highly complex, creative and mentally draining activity.
If you are in a software factory then you need to get out, those people don't value you.