Does MFP count all exercise calories as equal?

To answer your question, I’m not sure. However I wear a Garmin and I have had similar things happen where my Garmin’s estimated burn for the day was high so I was given extra calories that day even though I had a low activity day.

It's wise to be skeptical of "Calculated Calories Burned", regardless of the origin. They are just general estimates and can often be off substantially. Also, avoid comparing different types of activities from different sources... like say an "Elliptical workout" tracked in MyFitnessPal versus a "Run" tracked in MayMyRun.

One good use though is to compare workouts from similar activities day to day. For example, if you're using an Apple Watch while tracking a run/walk with MapMyRun, the app uses your heartrate, pace, distance, duration to estimate calories burned.

So if on Day 1, it says you burned 200 calories and Day 2... maybe 300 calories, then you can assume your day 2 was more intense than Day 1. However, you can't assume that you actually burned those calorie totals.

Why? - There's too many factors that come into play. I'll constantly override the numbers if I feel like they're too high or low. In general, on my workout days, I'll edit the calories burned to give me a budget of 1,900-2,000 calories for the day. And if it's a rest day, the calorie total stays at my estimated amount of 1,600 calories.

You'll know if your estimates are correct if you are losing weight. If you're weight loss has stalled or you've gained weight after several weeks... then an adjustment may be needed.

It seems like you have it synced to map my walk? Did you record any steps that day? Calorie adjustments from fitness tracked basically take what you say you've burned from both your MFP activity level and the exercise you log, and what they think you should have burned based on what they recorded, and they give you more or less calories based on that.

In your MFP app - do you have a StepSource set as your cell phone, and that's where it's seeing steps from?

If so (and it appears so) - there is some estimates from steps to distance to pace to calories burned from everything it saw. (which could be everything, could be missing chunks).

It's treating it like all other activity trackers - which have a base BMR level burn and all calories from distance stacked on top - or if workouts logged on that app then that's used.

That Total daily burned is sent to MFP (in this case just used by MFP since from the app) and compared to what your MFP settings estimated you'd burn at selected activity level with no workouts.
Workouts MFP knows about are subtracted out (since they are added again for eating goal) and an Adjustment is calculated.

You can tap and hold on that Adjustment field to get more details - that's the useful info - screen shot that and attach to post.

Lets say MFP estimated your sedentary activity level burn as 1960 - and you selected 1 lb weekly for 500 cal deficit.
Base eating goal 1460.

2nd day example could be (just using numbers I see):
App step-based Total burned 1941 - 1960 MFP estimated - 754 workouts = neg 773 adjustment

Base Eating goal 1460 - 773 adj + 754 workouts = 1441 new eating goal.

Now - that can literally happen if a workout knocks you out and you are very sedentary rest of the day.
Your workout may add extra burn, but being extra sedentary takes them away and more. But not likely that much more.

In this case I'm betting the app didn't see a big chunk of steps for the day and increasing the calories as it should.
Or flat out error in syncing as referenced above.

I haven't used MMW in a while - it doesn't attempt to keep track of daily calories does it?