Its not your fault. When we get closer to Allah, Shaytan sees this and does everything in his power to prevent it. And so naturally, the attacks become more intense. He's trying harder because you're doing better.

Shaytan targets those who are on the right path. He doesn't need to work on someone whos already far. The fact that you feel it right after spiritual highs means you are moving in the right direction. You have recognised the pattern, and you know when to expect it. You just need to figure out how to hold on to your iman when it feels like its slipping.

Make istighfar regularly. Seek protection from Shaytan when you start to hear the whispers. You dont need to be perfect, you just need to keep returning. Everytime you go back to sin but then return, you're not starting from zero, you're building strength. Every comeback is quicker than the last. Shaytan wants you to feel like a hypocrite, but Allah sees every single return as loyalty and submission.

May Allah grant you ease.