Umbrella for community-maintained tools available on Toolforge as https://toolforge.org subdomains (Not VPS-Projects which are https://foo.wmflabs.org/ and https://foo.wmcloud.org)
Please check first if there is a sub-project, talkpage, or another dedicated place to file bug reports, so you will get the attention of their developers. You can find the maintainers list for a tool at https://toolsadmin.wikimedia.org/tools/id/$NAME_OF_TOOL.
You can also find a list of tools (and their maintainers, source code, issue trackers) at https://toolsadmin.wikimedia.org/tools/
Note: Issues with the Toolforge infrastructure itself should be filed under Toolforge.