I just tried it out, and I can confirm that GPU training isn’t working with version 2.5.0 or 2.5.1 anymore.
import tensorflow as tf
tf.config.list_physical_devices('GPU')

Output: []
I’m not quite sure why this is, though, as according to this document 5, Tensorflow 2.5.0 supports the same version of Cuda and cuDNN than Tensorflow 2.6 (Cuda 11.2 and cuDNN 8.1)