Earlier quoted context omitted.
Nobody can work with engineers who are unwilling to commit to a schedule. Often it is very hard to make them commit and even if they do initially they often start missing deadline after deadline. A total nightmare for project management.
I don't agree. Its perfectly reasonable not to have any idea about an estimate until after an investigation or prototype has been produced. Demanding an estimate up front for something totally new just makes you look inexperianced or bad at managing engineers.
How well do the people executing the project know the codebase, data, and tech stack they're working with? How understood and confirmed are the requirements? The less those things are true, the less certain you can be with estimates. At the extreme, all you can do is poke the system and commit to providing feedback on what you've learned.
At the same time, you should be trying to make the system more lucid, both for yourself and new joiners on the team, such that estimates can become more accurate. The more senior you are as an engineer, the quicker you should be able to do that.