Is common for a journal to cancel an accepted review request when they have received a minimum number of required reviews, despite doing it two weeks before the deadline?

So this just happend to me (a non native speaker). Some months ago I published a paper in a journal and recently received a request to review a paper. At first I was uncertain to accept because I am still an undergraduate, but the paper was very related to my field, I still had fresh my knowledge of the literature, had a lot of free time because of health concerns, and also this other journal was from the same publisher (elSevier) of my publication, so I wanted to do my part and give back a proper review as the ones I received.I accepted, and the deadline was for 1 month. But two weeks later the journal cancelled the review with an automated message:"Thank you for agreeing to review the above-referenced manuscript. I am now able to proceed with evaluating this manuscript as I have received the minimum number of required reviews to make a decision.I would like to thank you for your services and I hope that I will be able to call on your support in the future."To be honest, I was excited to give my review and for that I had decided to take my time, do it well, and send it back after 3 weeks. I even took some online courses to learn about what is expected from reviewers...The paper was interesting and nobel but it needed major revisions, it was disorganized, the theory section was too short, there was not a related work section, the use of color in the figures was not consistent... But then the journal cancels the review request...Fortunately, I had a lot of free time, but I can't imagine a busy reviewer getting cancel requests just some weeks before the deadline. Reviews do take time, effort and more importantly, they are done for free.Because of this, if I ever get another review request (which I doubt it) I will probably decline.Have this ever happened to some of you? Was this behaviour from the journal ethical?