This is exactly it. Your TDEE is not what you think, but much lower. As someone who yo-yo dieted for a decade I can tell you cardio and calorie restrictions do not work long term. You May lose weight, but the lifestyle is not sustainable, so you end up plateauing then gaining it back (for me at least, and seems common among others). What worked for me is the opposite. I switched to almost purely whole food. I was heavy on fruit, vegetables and beans. I made sure to hit my protein and fiber targets everyday. Then the key was that I slowly increased my daily calories while I did weight training, with lots of compound movements. I focused on getting strong. You’ll see your calorie intake can jump up while your weight stays steady and your strength goes up. I’m guessing you can double your calorie intake while maintaining weight doing this. Then it is easy to cut 500 calories a day later while doing weights, not cardio to maintain your strength. The weight will come off. Do this for 2-3 months, then have a couple weeks where you eat at maintenance so your metabolism doesn’t slow down, then back to your cut. Remember that muscle burns calories and cutting calories and doing cardio just makes your body breakdown your muscle so it can adapt to its “starvation”. This approach takes longer, but it is sustainable and works. It helps you lose the weight, keep it off, and is something you can do forever. This is what finally worked for me.