Rich text field configuration does not inherit stylesheet

[Wiggee11]

Which Umbraco Forms version are you using? (Please write the exact version, example: 13.4.0)

15.2.0

Which Umbraco version are you using? (Please write the exact version, example: 13.5.2)

15.4.1

Issue summary

When specifying the RTE DataTypeId configuration to obtain RTE configuration, it does not pull in the defined stylesheet.

Specifics

When you set the RTE DataTypeId configuration appSetting to obtain configuration from an existing RTE, it doesn't include the defined stylesheets.

RTE in content:

RTE in Forms using same RTE Data Type:

Steps to reproduce

1. Create a RTE data type with a custom stylesheet
2. Update your appSettings Forms > RTE > DataTypeId configuration to use the RTE data type guid from step 1
3. Create a new form with the RTE data type

Expected result / actual result

Expected - The Umbraco Forms RTE should look and function exactly the same as the RTE data type it is inheriting
Actual - The Umbraco Forms RTE does not inherit stylesheets from the defined RTE data type