And let me preface that I do NOT mean weaknesses such as:
"I am bad at writing fighting scenes."
"I am not the best at writing dialogue."
"I find it difficult to commit to writing for a long period of time."
No. I mean weaknesses that are particular to you that may stem from your personality, lived experiences, or perhaps just the way your brain seems to work.
I'll go first!
One thing I personally struggle with is describing characters enjoy things that I personally hate or have at least a heavy dislike towards. Such as, the majority of alcoholic beverages. Or, for another example, coffee. The end result is that however much I rewrite such descriptions, I am never quite sure if it would actually make sense to someone who actually likes to crack open a beer, or enjoy a morning cup of dark coffee.
Another thing is, ironically, my good, vivid imagination. What this means is that I tend to go for certain cliches/tropes that are perfectly understandable and excusable in visual media, but are things that are very likely to be pointe doubt in literature. So, one example of this: my major characters NEVER wear helmets, unless the helmet itself is a part of characterization. Which isn't often.