I can talk to you about my experience.
Last year I was waitlisted.
I had no other interesting offer but I had a lot of things to do.
During this year, I completed my diploma thesis, I published two first authors papers and I did two internships (one industrial and one on the desired field of research with a reputable professor).
I thought that these things would be enough to make the transition from the waitlist to the acceptance list.
However, as you may have already understood I was rejected.
It may be the corona virus situation (more applicants and less spots as they have been transferred from the previous year), but maybe it wasn't. I cannot possibly know what the reason is.
If you have another offer that fulfills your standards, I would suggest you to take it.
Next year, you may have not even this one.
However, if you have not a good offer and/or you have something else to do that is quite good, I would suggest you to wait. Ideally, I would suggest you to work with a known professor and ask for his recommendation letter (I did not ask as it was very early during my internship). The corona virus situation may permit you to work remotely even for free for his/her reference letter (everyone needs free hands), I didn't have this luxury as I had to get paid.
Concluding, I would not have high expectations on this. I had, it is not healthy and it is not realistic some times.
Last year, I hadn't take my applications very seriously. This year I did and I have a great offer.
I hope that my answer will help you!