Cortisol increases in the morning, and if you don’t eat, your adrenals overwork to compensate, so you feel energetic. Sounds like you’re not keto-adapted, your body doesn’t fully utilize ketones from fat.
Working out fasted is a huge mistake, especially if you’re not keto-adapted. You’re more likely to burn muscle via gluconeogenesis.
Personally, I’ve made the same mistake, after 2-3 months of IF and working out fasted, I was cranky and exhausted.
The best thing you can do is eat a small amount of fatty protein when you wake up to calm your adrenals. Believe it or not, you’ll achieve deeper ketosis that way. Or at least consume some coconut oil or mct oil before your work outs, take deep breaths and try to be as relaxed as possible, that way your body will learn to use the fat.

It sounds like you’re cortisol driven. Coffee stimulates the adrenals even more.

There’s absolutely no problem should one work out fasted. It’s actually beneficial and can increase levels of HGH.

I fast for 20 hours a day and do my work out between hours 16 and 18 of my fast. I have much more energy, stamina and strength doing fasted workouts.

Keto or non keto when you eat your gut uses blood to do its digestion and nutrition absorption gig. That’s why you get postprandial narcolepsy (wanting a sleep after you eat a meal). I have always worked out better faster than fed, keto or non keto.