Steps to reproduce the issue

In an arbitrary form definition XML file, add 1 of the 3 variations for the field for a color picker:

Variation 1

<field 
name="color" 
type="color" 
default="rgba(255, 40, 40, 0.5)" 
format="rgba" 
label="FORM_LBL_MAP_COLOR"   
hint="FORM_LBL_MAP_COLOR" />

Variation 2

<field 
name="color" 
type="color" 
default="rgba(255, 40, 40, 0.5)" 
format="rgba" 
label="FORM_LBL_MAP_COLOR"   
hint="FORM_LBL_MAP_COLOR" 
onchange="(function(){console.log('onchange triggered')})()"/>

Variation 3

<field 
name="color" 
type="color" 
default="rgba(255, 40, 40, 0.5)" 
format="rgba" 
label="FORM_LBL_MAP_COLOR"   
hint="FORM_LBL_MAP_COLOR" 
onchange=" onchange=&quot;(function(){console.log('change')})()&quot;"/>

Expected result

Variation 1 - Works as expected

<input type="text" name="jform[color]" id="jform_color" value="rgba(255, 48, 41, 0.5)" placeholder="FORM_LBL_MAP_COLOR" class="form-control minicolors rgba minicolors-input" data-position="default" data-control="hue" data-format="rgba" size="25" data-opacity="0.50">

Variation 2 - should render the onchange properly

<input type="text" name="jform[color]" id="jform_color" value="rgba(255, 48, 41, 0.5)" placeholder="FORM_LBL_MAP_COLOR" class="form-control minicolors rgba minicolors-input" data-position="default" data-control="hue" onchange="(function(){console.log('change')})()" data-format="rgba" size="25" data-opacity="0.50">

Actual result

Variation 1 - Works as expected

<input type="text" name="jform[color]" id="jform_color" value="rgba(255, 48, 41, 0.5)" placeholder="FORM_LBL_MAP_COLOR" class="form-control minicolors rgba minicolors-input" data-position="default" data-control="hue" data-format="rgba" size="25" data-opacity="0.50">

No console activity is expected.

Variation 2 - the onchange is not rendered properly, note: onchange= is missing after "hue"

<input type="text" name="jform[color]" id="jform_color" value="rgba(255, 48, 41, 0.5)" placeholder="FORM_LBL_MAP_COLOR" class="form-control minicolors rgba minicolors-input" data-position="default" data-control="hue" (function(){console.log('onchange="" triggered')})()="" data-format="rgba" size="25" data-opacity="0.50">

It is expected to see "change" logged to the console, but it does not

Variation 3 - the desired rendering of the field is achieved by tricking the form parameters

<input type="text" name="jform[color]" id="jform_color" value="rgba(255, 48, 41, 0.5)" placeholder="FORM_LBL_MAP_COLOR" class="form-control minicolors rgba minicolors-input" data-position="default" data-control="hue" onchange="(function(){console.log('change')})()" data-format="rgba" size="25" data-opacity="0.50">

It is expected to see "change" logged to the console and it is

System information (as much as possible)

Joomla 4.3.3 (also the same behavior on Joomla 4.2.2)

Additional comments

<field 
name="color" 
type="color" 
default="rgba(255, 48, 41, 0.5)" 
format="rgba" 
label="FORM_LBL_MAP_COLOR" 
hint="FORM_LBL_MAP_COLOR" 
onchange="(function(){console.log('onchange triggered')})()"/>

generates the proper:

<input type="text" name="jform[color]" id="jform_color" value="rgba(255, 48, 41, 0.5)" placeholder="Color" class="form-control minicolors rgba minicolors-input valid form-control-success" data-position="default" data-control="hue" onchange="(function(){console.log('onchange triggered')})()" data-format="rgba" size="25" data-opacity="0.50" aria-invalid="false">

In Joomla 5.0.0 Alpha 3