put in 2week & got terminated

i just started this job 3 weeks ago, found a better opportunity & asked nicely to put in my 2 week notice. i thought this was the right thing to do. i thought giving a notice would help the company align future employees. i guess not. my team lead came back after i asked & told me he had bad news, i didn’t expect this. i just wanted to be kind, i just wanted to help out the company. i guess a 2 week notice is now nothing but useless.