This has nothing to do with electrum servers. It's an issue with the SSL certificate that bitpay is sending to electrum. According to electrum you don't trust the certificate authority that issued that cert.
Indeed, this seems to be what's going on based on OP's description.
I don't know how you would go about fixing it in windows 11.
Electrum does not use the operating system's CA store anymore. The python certifi package is used, which bundles Mozilla's CA root store. certifi is a required dependency, and Electrum uses it as the CA store everywhere internally.
This has been the case since around version 3.3. Before that, for some network requests the certifi (/requests) store was used, for other Electrum implicitly used the OS store. Using the OS store used to cause weird issues on some systems.
https://github.com/spesmilo/electrum/blob/8eb3c43603ed1915fa3e0b8d17c9dbeb183270c5/electrum/util.py#L88https://github.com/spesmilo/electrum/blob/8eb3c43603ed1915fa3e0b8d17c9dbeb183270c5/contrib/deterministic-build/requirements.txt#L15-L16Every version of Electrum ships with some specific version of certifi, so over time that CA store might get out of date, for an older release.
(At least when running the binaries. However if you e.g. install from a Linux distro, they might update the version of python3-certifi that they package independently of Electrum.)