@Bakual
To test, after apply your patch, i have edited the file:

/administrator/components/com_users/forms/user.xml

To:

		<field
			name="name"
			type="text"
			label="COM_USERS_USER_FIELD_NAME_LABEL"
                        translateLabel="false"
			required="true"
			size="30"
		/>

The oputput without issues (also validating as not allowed if the field is empty), and "Save" without issues or log warning:

I have also tested what we basically need to display without trigger log warnings:

		<field
			name="name"
			type="text"
		        label="&lt;strong&gt;REF_KEY_TO_DISPLAY&lt;/strong&gt;&lt;br&gt;Some string to translate."
                        translateLabel="false"
			required="true"
			size="30"
		/>

To test it under failure now i use: translateLabel="true" with the next string:
Any string with 2 placeholders %1$s %2$s before a grammar comma, for example.

	<fieldset name="user_details" label="COM_USERS_USER_ACCOUNT_DETAILS">
		<field
			name="name"
			type="text"
			label="&lt;strong&gt;REF_KEY_TO_DISPLAY&lt;/strong&gt;&lt;br&gt;Any string with 2 placeholders %1$s %2$s before a grammar comma, for example."
                        translateLabel="true"
			required="true"
			size="30"
		/>

@Valc Do I understand right that your test was successful? If so, please mark your test result in the issue tracker here https://issues.joomla.org/tracker/joomla-cms/35900 , using the “Test this” button, then selecting the appropriate test result and finally submitting. Thanks in advance.

I have tested this item ✅ successfully on d60a166

I have tested this item ✅ successfully on 0fad445

RTC. Thanks!

Thx