For me it’s Ctrl + C / V. I will frequently hit Ctrl + C when I want to paste, and some software helpfully copies a blank line to the clipboard if nothing is selected, thus erasing whatever I copied.
I miss shift-insert/shift-delete.
From the days when both hands were on the keyboard.
Get a clipboard manager. Being able to access my last 20 copies instead of only 1 is definitely something I wish I set up a decade before I did.
Not only useful for mistakes but also just if you jeed to eg copy someone's bank info to separate fields without doing 4 switches from invoice to bank app