Our Jenkins sits behind a firewall, so we have to configure a proxy to access external resources, also git repositories.
After upgrading from 2.89.4 to above LTS I noticed that pipeline jobs were hanging because they failed to fetch the Jenkinsfile from a git repo. It turned out that proxy settings were not used. I managed to work around that by disabling "Lightweight Checkout".
After that the pipeline failed to load libraries, again because of missing proxy settings.
All the problematic repositories could be cloned by "plain" git checkout steps, so my proxy setting are in fact correct, they are just not applied.
many thanks, Holger