MyFitnessPal, eh?
The calories on your MFP and Fitbit apps are likely going to be different because your calorie allowance bases on how many calories you burn out. I don't know if MyFitnessPal does this same thing.
MyFitnessPal seems to nicely integrate wth Fitbit

You could ask MFP about it. Or contact Fitbit support.
Third-party integrated software support teams are the best resource to optimize when you need help.

Have a good day
🙂