Invalid environment name

Since today, this error message has surfaced:

> The environment name provided exceeds the character limit of 16 or has invalid character(s). Valid characters are 0-9, a-z, and A-Z. Please provide a valid name for your environment like 682

12 days ago, using an identical YAML, this was not the case.

**To Reproduce**
Steps to reproduce the behavior:
1. Run this:

- GitHub Actions or Azure Pipelines workflow YAML file
```
name: Validate Pull Request

on:
pull_request:
branches: main

jobs:
validate-pull-request:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v3
- uses: actions/setup-node@v3
with:
node-version: 16
- uses: pnpm/action-setup@v2
with:
version: 7

- run: pnpm install
- run: pnpm run formatcheck
- run: pnpm run stylecheck
- run: pnpm run typecheck
- run: pnpm run lint
- run: pnpm run test

build-and-deploy-preview:
if: contains(github.event.pull_request.labels.*.name, 'pr-environment')
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v3
- uses: pnpm/action-setup@v2
with:
version: 7

- run: pnpm install
- run: pnpm run build

- uses: Azure/static-web-apps-deploy@v1
with:
azure_static_web_apps_api_token: ${{ secrets.AZURE_STATIC_WEB_APPS_API_TOKEN }}
action: upload
app_location: "build" # App source code path
output_location: "" # Built app content directory - optional
deployment_environment: preview
skip_app_build: true
```
- staticwebapp.config.json file
```
{
"navigationFallback": {
"rewrite": "index.html",
"exclude": ["*.{svg,png,jpg,gif}", "*.{css,scss}", "*.js"]
}
}
```
- source repository if it's public
N/A (private)

**Expected behavior**
Successful deployment of _preview_ environment.

**Screenshots**
Not working, as of today:

Same branch, working, as of 18 days ago:

**Device info (if applicable):**
- N/A (whatever the Github hosted agent runs)

**Additional context**
I've tried pinning the action version to a commit from a known good time, but it seems to have no effect, leading me to think that the problem is further upstream.