I had visited the USA 4 times last year but only stay 5 days each time. My last visit was in December 2019 when I stayed for 3 days to do some shopping and return to my home country.
This year I want to visit a friend in February to spend my birthday for 5 to 7 days. Will this travel pattern draw attention? Or will is be OK?
There’s nothing inherently suspicious in that pattern. The visits have been short and not particularly frequent. In total you spent about 20 days in the US during the entire year; you’re nowhere close to the point where it might look like you’re doing visa runs or taking other steps to try to game the system.
On the contrary, because you have a history of visiting the US for less than a week at a time, an immigration officer is more likely to believe your statement of intention to visit for 5 to 7 days. Enjoy the birthday celebration.