user23742: I just bought a Feelworld MA7 and did some test yesterday regarding false colors.
Here are my tests:
1) video capture of the scene, together Final Cut Pro X's oscilloscope:

2) photo of what the Feelworld MA7 field monitor was displaying:
 
Close-up on the scale:

We can see that although pink should be for totally black areas (IRE < 0), MA7's false Colors show pink even in areas holding information, like the left side of the t-shirt which, according to the oscilloscope (and according to our eyes), hold some luminance values.
To push the test a little bit further, I used a lut which applies false colors onto clips in FCPX (https://luts.iwltbap.com/false-color-lut/). Here's the result with the corresponding scale (I think it's Atomos' scale):

In this case, the results are much more intuitive (and better corresponding to the oscilloscope): nowhere do we see dark purple (IRE < 0 on this scale).
Why is that? And ultimately, can I trust the Feelworld MA7 field monitor to help me accurately expose my scenes?

user23797: Such cheaper monitors often don't have enough power to calculate it correctly.
Often they are just added as a sales pitch.
I wouldn't totaly trust it, but you can take it as a rough estimate.

23742: <p>I just bought a Feelworld MA7 and did some test yesterday regarding false colors.</p>

<p>Here are my tests:</p>

<p>1) video capture of the scene, together Final Cut Pro X's oscilloscope:
<a href="https://i.stack.imgur.com/GOotd.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GOotd.png" alt="video capture of the scene, with Final Cut Pro X oscilloscope"></a></p>

<p>2) photo of what the Feelworld MA7 field monitor was displaying:
<a href="https://i.stack.imgur.com/5bCOI.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/5bCOI.jpg" alt="enter image description here"></a> </p>

<p>Close-up on the scale:</p>

<p><a href="https://i.stack.imgur.com/6Cv4c.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/6Cv4c.png" alt="enter image description here"></a></p>

<p>We can see that although pink should be for totally black areas (IRE &lt; 0), MA7's false Colors show pink even in areas holding information, like the left side of the t-shirt which, according to the oscilloscope (and according to our eyes), hold some luminance values.</p>

<p>To push the test a little bit further, I used a lut which applies false colors onto clips in FCPX (<a href="https://luts.iwltbap.com/false-color-lut/" rel="nofollow noreferrer">https://luts.iwltbap.com/false-color-lut/</a>). Here's the result with the corresponding scale (I think it's Atomos' scale):</p>

<p><a href="https://i.stack.imgur.com/s2CMK.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/s2CMK.jpg" alt="enter image description here"></a></p>

<p>In this case, the results are much more intuitive (and better corresponding to the oscilloscope): nowhere do we see dark purple (IRE &lt; 0 on this scale).</p>

<p>Why is that? And ultimately, can I trust the Feelworld MA7 field monitor to help me accurately expose my scenes?</p>
 23797: <p>Such cheaper monitors often don't have enough power to calculate it correctly.
Often they are just added as a sales pitch.
I wouldn't totaly trust it, but you can take it as a rough estimate.</p>
