Slow WordPress User Password change

Changing the WP user password in wp-admin (User > Profile) and even the wp-cli is extremely slow, probably caused by the firewall and sendmail. Normally the Update was instant. using wp-cli it showed:

time wp user update "User Name" --user_pass=password --allow-root
Success: Updated user 1.

real    1m0.330s
user    0m0.003s
sys     0m0.012s

So it took 1 minute to update the (insecure) password. In the web interface it appears faster yet there is no page reload upon password change as it would be normally. Mostly I get logged out of the interface probably due to expired cookie. It appears that the access log switches between http2 and http3 and page redirect fails with admin-ajax.php. Here is part of the access log.

"POST /wp-admin/admin-ajax.php HTTP/2.0" 200 68 "https://
"POST /wp-admin/admin-ajax.php HTTP/3.0" 200 71 "https://
"POST /wp-admin/admin-ajax.php HTTP/2.0" 200 68 "https://

I'm using Ubuntu 24.04 with the latest WordOps v3.21.3. Installed via wo stack install and the site using PHP8.3 and letsencrypt. Changes to PHP 8.2, 8.1 and 8.0 showed the same slow password problem so this is either a crypt or DB issue?

I didn't find other reports of such behaviour yet, didn't get info inside the WebDeveloper tools in browsers so some hints how to debug this are appreciated.

Edit1:
The wp-cli --debug option also shows nothing strange going. All is fine, until the user update command is run. Then it needs 1 minute which is way too long and like a timeout. Reading the function source I now suspect that this is caused by not being able to send an email?

Some hints for inspection:
WordOps installs sendmail with Port 587 yet the official firewall rules don't include that port. It looks like the reason f

wp-cli output

...
Debug (commands): Adding command: enable in qm Namespace (0.232s)
Debug (bootstrap): Running command: user update (0.232s)
Success: Updated user 1.

real    1m0.381s
user    0m0.004s
sys     0m0.015s

Edit2: using sendmail from the CLI has around the same timeout as in WordPress. I will now try to fix the email provider. I suggest, that for a flawless WordPress install some changes would have to be made in core/sendmail.py so a slow profile update/timeout can be prevented.