This 403 on treeinfo can be inspected when you are using your proxy.
192.168.2.13 - - [15/Jan/2022:02:40:31 +0100] "GET /centos/7/os/x86_64/.treeinfo HTTP/1.1" 403 3992 "-" "urlgrabber/3.10"
192.168.2.13 - - [15/Jan/2022:02:40:31 +0100] "GET /centos/7/os/x86_64/treeinfo HTTP/1.1" 403 3989 "-" "urlgrabber/3.10"