Working out while on a deficit?

Not technically turning fat to muscle but burning fat while buildung muscle.

For those who have quite some fat to lose and are novice to exercise, lifting weights while on a deficit will help them build muscle while losing fat. The process gets much harder once you reach a more desirable body fat %, but I've read of cases here where it can be done.

Was wondering what the point of doing resistance training while eating at maintenance or even at a deficit? Like push ups, planks, bicep curls, squats etc

To "maintain" your current muscles, fire up the metabolism, and keep your body in maintenance mode. It doesn't always have to be about getting bigger, stronger, faster - or about losing weight. There is nothing wrong with maintaining - as that is an excellent goal for a majority. You could substitute other exercises as well in your question of "what's the point of doing any training while eating at maintenance?" Whether we call it to improve overall health, lifestyle of staying fit and healthy, or maintenance - it's a prime goal to achieve.

In terms of the exercise while eating "even at a deficit", a lot of the same still applies - trying to maintain the muscles you do have while running a caloric deficit to trim the fat. The resistance training will fire up the metabolism and the post exercise "burn" to help with the caloric burn - and will contribute to maintaining the current muscle you do have.

Compare one person who loses weight, or maintains weight through diet alone and does not exercise outside of their daily routine to one who loses weight, or maintains their weight while also using exercise as part of their daily routine. One will have a lot more spring in their step compared to the other. At least that's what I have felt at various times in my life having done it 'both ways'.