APT fails to download Jenkins from upstream repo

Error: /Stage[main]/Jenkins::Package/Package[jenkins]/ensure: change from 2.235.1 to 2.263.1 failed: Could not update: Execution of '/usr/bin/apt-get -q -y -o DPkg::Options::=--force-confold 
--force-yes install jenkins=2.263.1' returned 100: Reading package lists...
Building dependency tree...
Reading state information...
The following packages will be upgraded:
  jenkins
1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 66.9 MB of archives.
After this operation, 833 kB of additional disk space will be used.
Err:1 https://pkg.jenkins.io/debian-stable binary/ jenkins 2.263.1
  Received HTTP code 403 from proxy after CONNECT
W: --force-yes is deprecated, use one of the options starting with --allow instead.
E: Failed to fetch https://get.jenkins.io/debian-stable/jenkins_2.263.1_all.deb  Received HTTP code 403 from proxy after CONNECT
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

For some reason, the exception in our proxy is not working correctly.