Do you mean that the model output is different for the same input? That is unexpected for a ResNet with model.eval().
e.g., what do you get when you run something like
inp = torch.randn(1, 3, 224, 224, device='cuda')
model.eval()
out1 = model(inp)
out2 = model(inp)
print(torch.allclose(out1, out2))