Do I need an antivirus for a MacBook Air? If so which one?

I have a MacBook Air M1 2020 and I fear it might be getting worse ever since I finished my MacKeeper subscription a few weeks ago. I decided not to renew my subscription because it was taking too much memory and every time I refreshed memory space it would always go back to being slow again. I hear that getting an antivirus for MacBook is not a good idea as it hinders the security that is inbuilt in Mac products but I don't know the validity of that claim. What is my best course of action?