How to resolve OOM (out of memory) issues when flux2klein9b processes scaled-down images?

Here are the observed scenarios: In the same workflow, scaling a 4K image down to 1.5K or even 1K before feeding it into flux2klein9b causes OOM. If I first scale the 4K image down to 1.5K in one workflow, and then process that downscaled image in a separate (second) workflow, OOM does not occur. In the same workflow, scaling the same 4K image down to 2K and processing it with the Qwen model does not cause OOM. The Qwen model is ~16.6 GB, while flux2klein9b is ~9.5 GB.