Feeling lethargic + anxious at the gym lately… anyone else go through this?

I don’t really know what changed, but lately I feel super lethargic in the gym and I’m starting to get anxious before my workouts. I used to actually look forward to lifting, but now I kind of dread it and even feel scared when I’m about to start.

For example, hip thrusts used to be my favorite when I was lifting around 10kg because I could really feel them. Now I’m at 43kg and I honestly dread it. By like 5 reps I’m already out of breath and it feels so heavy. Today I got to 8 reps, but during the set I don’t really feel it working—just that it’s getting harder and harder to lift. Then a few minutes after, I finally feel it in my glutes.
Because of that, I end up feeling disappointed in myself, like I didn’t perform well or had a bad workout. Even if I \\\*do\\\* feel it after, the whole session just feels “off” because I felt lethargic the whole time.

I also notice I feel really low energy mid-workout, especially when I know I still have more exercises left. It’s like I lose motivation and everything feels heavier mentally and physically.

I’ve tried sipping an energy drink during workouts and eating bananas / candy for quick energy, but I still feel lethargic and kind of anxious.
Has anyone else gone through this? How did you deal with the anxiety/dread and get your energy back?

edit: I just finished my cardio tonight after lifting, and I noticed something weird. I \\\*was\\\* feeling lethargic during my lifts, and even going into the StairMaster I still felt kind of drained. But after doing like 50 minutes of StairMaster, I suddenly feel… alive? Like my energy just switched on out of nowhere. I don’t even feel as exhausted anymore compared to earlier in the workout. Not sure what that means but it was such a strange shift.