What about this:

WARNING
There are known non-determinism issues for RNN functions on some versions of cuDNN and CUDA. You can enforce deterministic behavior by setting the following environment variables:
On CUDA 10.1, set environment variable CUDA_LAUNCH_BLOCKING=1. This may affect performance.
On CUDA 10.2 or later, set environment variable (note the leading colon symbol) CUBLAS_WORKSPACE_CONFIG=:16:8 or CUBLAS_WORKSPACE_CONFIG=:4096:2.
See the cuDNN 8 Release Notes 4 for more information.

Ref: LSTM — PyTorch 1.7.0 documentation 12