Losing confidence after a series of paper rejections I don't think I have a concrete question to ask but I want to hear other researchers' opinions. I am pretty sure that there are many researchers who went through this and others will go through it in the future unfortunately.
I am a postdoc researcher with a limited contract and aim to apply for professorship positions. Therefore, I am actively submitting papers (working more than my contracted hours as there are no PhD students to co-supervise and publish papers with) to come up with a good and long list of publications. However, a lot of my papers are getting rejected with a huge disparity in the reviewers' scores. As a reviewer in almost all conferences I submit my work to, I find that my submission is better or equal to top accepted papers (I don't know whether this is a bad lcuk or just an illusion).
I focus mainly on top conferences with acceptance rates of less than 30% or 25%. I was almost sure that my last paper would be accepted because I am an expert in the area and because I learnt to assess paper quality, but it got rejected a few days after another rejection. Now, I am doubting my research capability (although I used to publish easily to these conferences when I was a PhD student). I am wondering whether I am a bad researcher or just an unlucky author.
This sounds like a pretty common case of the human condition.  In my single days, I used to think of dating like &quot;strikes and gutter balls&quot;.  That is, either I was getting many dates in rapid succession or going through a prolonged dry spell.  In the former, I was feeling pretty good about myself and was quite down in the latter.
In my current research days, I find a similar emotional oscillation.  This is the nature of research, in my opinion, and it builds character.  You actually sound quite productive, and the results will come.  In fact, I would encourage you to try to get more enjoyment from the process of seeking truth rather than putting all your eggs on the often opaque 'accept/reject' decision.  If I may with another analogy, it's like learning golf.  It's a slew of mishits, duffs, shanks, slices, hooks, flubs, and ineptitude until suddenly you smash a beauty down the fairway and are the envy of your friends.  If the one great shot makes up for the many bad shots, you're hooked.  If not, you're probably going to quit.
Also, pragmatic advice holds: get sleep, review diet, practice self-care, take mental health breaks, seek advice from colleagues/advisors, confirm writing and presentation adequately represents results, etc.