There’s a number of different, potential causes of a directional light leaking. It’s best to provide more information about the scene in regard to the specified problem. Here’s some info to upload screenshots of:
Directional Light settings (all its basic settings, and all settings under Lighting). Don’t need to include Cascaded Shadow Maps, Distance Field settings, or the other settings further down the details panel.
Post Process Volume settings (include all enabled GI settings, enabled Exposure settings, any Color Correction settings if they’re enabled, and the “Post Process Settings” dropdown such as Blend Radius, Blend Weight, Unbound, etc).
Skylight settings (include everything up top and under Lighting). Another user I just read had a similar issue with the interior of a dark room becoming lit when it should be black. An experienced user replied that it may be the skylight due to it using cubemap to light everything. The cubemap takes every mesh / material into account and mixes it in the cubemap to light things, so it can potentially cause over-brightening of certain meshes / areas.