Loss shooting up

Hi. I’m training a simple Autoencoder on Cifar10 with mse loss using Pytorch lightning. After tinkering around the hyperparameters my loss suddenly starts to shoot up out of the blue after about 20epochs for no apparent reason. I am able to control it by clipping gradients but wanted to understand what I’m doing wrong that the model has started to lose stability?

autoencoder control deeplearning lightning loss pytorch pytorch lightning reason simple training