I have lost my passion for [English writing | writing in English] today. I have lost my passion for [English writing | writing in English] today.

“Lost” is unnatural here because, if you “lost” it today, that means you had it at some point in the beginning of the day, and then you lost it—the loss occurred today. “Have lost” is OK, because it describes a state of loss, not the time the loss occurred. Alternatively, you could say you “have no passion for writing in English today” or “I don’t feel like writing in English today.” “English writing” could mean “the act of writing in English” or “(the act of reading) things that are written in English.” “Writing in English” is less ambiguous.

I lost my passion for English writingdon't feel like writing in English today. I don't feel like writing in English today.

What you wrote was technically correct, but it was too dramatic for the context.

I lost my passion for English writingmotivation to write English today. I lost my motivation to write English today.

I lost my passion for English writingwriting in English today. I lost my passion for writing in English today.

I edited the phrase to sound more natural. It is technically correct to say that you lost your passion for English writing today, but it sounds awkward in your situation.

I don't know why, m. Maybe it's because I've been on a diet recently. I don't know why. Maybe it's because I've been on a diet recently.

I don't know why, m. Maybe it's because I've been on a diet recently. I don't know why. Maybe it's because I've been on a diet recently.