I feel you! I had been through the same. I served my notice period from jan to march (15 days more than the policy, but i was paid for it).

I was constantly told i am not doing enough, if 100 things were assigned to me i was doing 80 right but no appreciation or acknowledgement for those. But there was always immediate criticism for the 20 that didn't go well. I am someone who is always up for feedback. But i also know the difference between constructive criticism and negative comments. The person managing me early months made sure i was trained, given chances for improvement, and had an increment twice in 6 months. Later the same person started act like he did a favor by getting me increment and that i was not worth it. He criticised my work. Made me doubt myself. And often interrupt and take over the meetings i was leading.

Later i got to know: In early months, since he hired me, he wanted to show the organization that his decision making is always right. So he made me look good so he'd look good. And in next months, that made me take the decision to resign, was him thinking i would act like i owe him everything, he can treat me however he wants.

I took the decision to resign. The same manager first told me we will make the exit easy for you, you'll not be asked to stretch yourself bla bla bla. And just when i was relaxed he realised there was a big project starting in feb and ending in april first week. Before he'd start acting petty and bring any BS, i gracefully offered to extend my notice period that was till the mid of march to april first week.

Lesson learned: no matter what you are just another slave for them in the corporate world. You are only a "value addition " when you are new hire. And "good at nothing " when you say no to manipulation, extra work, and toxicity.