### Steps to reproduce

1. Login as an admin

2. Go to Administration > Users

3. Open the profile page of Begin of the insertion~~aEnd of the insertion Begin of the deletion aEnd of the deletion users who signed up through Begin of the insertionOIDC~~ _your own accout_End of the insertion Begin of the deletion OIDCEnd of the deletion

4. Change their username Begin of the insertion~~or email~~End of the insertion Begin of the deletion or emailEnd of the deletion


### What is the buggy behaviour?

* UI is not greyed out

* It looks like admins can make this change on OP but after saving they see an error message


### What is the expected behaviour?

1. Fields that can't be updated are greyed out/disabled


###

### Screenshots and other files

<img class="op-uc-image op-uc-image_inline" src="/api/v3/attachments/918538/content">

### Environment information

**OpenProject version**

Core build

[93d007f7a6d319b181c5b7c7cdfe3381c2478021](https://github.com/opf/openproject/commits/93d007f7a6d319b181c5b7c7cdfe3381c2478021)

Product version

[2f57a70dd455e8ac9de62708487287ff0e3e69a1](https://github.com/opf/saas-openproject/commits/2f57a70dd455e8ac9de62708487287ff0e3e69a1)

Core version

OpenProject 17.1.0

**Browser**

* [ ] Chrome
* [x] Firefox
* [ ] Safari
* [ ] Mobile Safari
* [ ] Other (please specify)

**Operating System**

* [x] Windows
* [ ] Mac OS X
* [ ] Mobile iOS
* [ ] Mobile Android
* [ ] Linux (please specify distro)
* [ ] Chrome OS
* [ ] Other (please specify)