Either your batteries were old[1], or you're overlooking something else that might have caused increased self-discharge, such as high humidity. Some will say it was a myth, but it was true at one time.

What is a myth is that storing cylindrical cells in your freezer will slow self-discharge, and while it is proven cold storage will reduce self-discharge, the problem with a consumer freezer or refrigerator is that they are humid, so any gains the cold would provide are more than defeated by the humidity, which not only will increase self-discharge, it can damage and short a cell. The humidity in a consumer-grade freezer drastically increases to 80%-95%RH twice a day and slowly drops over several hours. The best place to store cells is in a cool, dry location. And cells are cheap and readily available, and storing cells for years in a freezer, even if it worked, would be wasting a ton of energy just to save a tiny amount of energy, which, again, wouldn't happen anyway.

[1] https://www.mcgill.ca/oss/article/general-science-you-asked/...