Phishing is when hackers buy a domain name that looks similar to the original one and also make the web page looks the same and they try to make you upload your wallet file there and put your password etc.

I don't think MyCrypto could be considered as an online wallet because your info is not stored there but my point is, MyCrypto looks different and the domain name is somehow different and short and hard to find similar to it and until now, I haven't seen phishing attempts targeting it so it could be much safer to use that for now.