Just updated Jenkins to 2.263.2 and also updated all the plugins, same issue.
The test code in your comment doesn't seem to match this issue precisely though, to elaborate:
Section title: "Write to all available streams and return the standard output"
def stdout = powershell(returnStdout: true, script: '''
# Enable streams 3-6
$WarningPreference = 'Continue'
$VerbosePreference = 'Continue'
$DebugPreference = 'Continue'
$InformationPreference = 'Continue'
Write-Output 'Hello, World!'
Write-Error 'Something terrible has happened!'
Write-Warning 'Warning! There is nothing wrong with your television set'
Write-Verbose 'Do not attempt to adjust the picture'
Write-Debug 'We will control the horizontal. We will control the vertical'
Write-Information 'We can change the focus to a soft blur or sharpen it to crystal clarity.'
The article states that running this code should result in the console output:
ERROR: script returned exit code 1
However, when I copy / paste this code verbatim into my pipeline script within Jenkins on Windows 10 (https://i.imgur.com/8yYk7gE.png) and run it, I get (https://i.imgur.com/gsoCxq8.png):
Could you please try simply copying / pasting the exact example code into your Jenkins instance and seeing if the pipeline shows a success or failure at the end? The point I'm trying to make is that the Jenkins article states this exact code should result in a failure, but in reality the code returns a success. I am not sure if the article is simply incorrect, if the Jenkins behaviour has changed since the article was written, etc.