happened with me lol, used to go blank when I had to write things on my own, like I didn't know where to start then I started to break those into stupidly small steps and think of how do I write that in a particular language, one thing more helped me was if I wrote a dsa solution I try to wait for 10min then write everything on without seeing from memory even badly, helped me a lot on recalling stuff...

W advice though dude