The terms "memory leak" and ".NET application" are not used together very often. However, we recently had a spate of out of memory exceptions in one of our .NET Core web applications. The issue turned out to be caused by a change in behavior in Entity Framework Core, and whilst the eventual solution was incredibly simple, the journey to get there was both challenging and interesting.
The system itself is hosted in Azure and is comprised of an Angular SPA front-end and a .NET Core API on the back-end, using Entity Framework Core to talk to an Azure SQL Database. As a software consultancy specializing in .NET development, we've written many similar applications before.