My most common edit is to FORGET to put in a capital I for I =me, this is because I do it automatically when writing with pen and paper, it is usually drilled into all native English speakers who attended school, but I very often forget to hold down the caps key to get the capital I=me.
I actually forgot and had to go back three times up until this point, to use CAPS I=me.
When ever I notice this mistake even at a later time/date I edit and correct, because we cannot keep reminding English learners about this and then we ourselves make the same mistake.
I also constantly reread what I have written previously and rewrite it, if I think it can be made clearer. This I do anyway and is not related to being on italki.
I deleted many comments when I first arrived here which coincided with testing 'Grammarly' that was forever trying to force me to say and write words when I knew what words I wanted to write and for what reason.
'Grammarly' is good but it forces you to write only in a certain style. It has been taken off my computer since about after a month or two of arriving here.
I see nothing wrong or embarrassing about editing. It happens in normal daily life especially when dealing with officialdom and official things where you wish to not make costly mistakes and even the most qualified teachers and professors make mistakes.
Add to this the fact that English is a confusing language in many ways and anything and everything written or spoken can be misunderstood by anybody at any time. No speaker or writer is immune from this, A1 to C2 inclusive and professors. I have had university teachers lectures and professors admit to making mistakes and informing to disregard the last lesson and given out corrections.
NB one edit so far after submitting I noticed a missing word. If I did not edit learners would have a bad sample sentence to copy.