Has anyone experienced this before: doing more poorly the more the game is played?

I feel like my skills are worsening even though I have been trying to practice more. I set aside time to train my 4x and 6x spray in the training server and I have been playing more TDM, while reducing the amount of scrimmages.

Not surprisingly, I’d expect my mechanical skills to improve considering the time I dedicated to it. However, today I hopped onto a TDM match with my friend (who have been studying while I was practicing PUBG) and did way poorer than him. He plays the game very occasionally and while he is decent, he probably never bothered doing any training.

Even worse, when I perform poorly, I will get frustrated, and somehow perform even more poorly.

Does anyone have any idea how do I deal with weakening skills? Should I practice more or switch ways of training? Or should I do away with scrimmages completely and focus on practice?

TL;DR, skills worsening despite effort put in

Good players, what advice can you give? I’d love to hear about how you reached your skill level. Please help out this struggling pleb and thanks for reading (: