When you are using a Next-gen project (Team Managed Project as they are called now) and you create a field of type People to use on your issues, this field will not keep its history correctly.
When you change the value of this field, the changelog will include an entry for this but it will not display the user names.
This is how it looks in the History tab of the issue:

And this is what you get from the REST API:
"created": "2021-06-18T11:42:48.003+0300",
"items": [
{
"field": "Responsiblesss",
"fieldtype": "custom",
"fieldId": "customfield_10065",
"from": "[5b88ff0d9e23562b1dbxxxxx, 5df778e2588f6e0cb03xxxxx]",
"fromString": "",
"to": "[5b88ff0d9e23562b1dbxxxxx]",
"toString": ""
}
]
You see? It keeps the account IDs, but not the user names? Why is that?
Is this a bug?