not able to loose weight even after eating less & working out daily

I’ve been working out daily for the last 1.5 months and I usually burn around 400–600 calories at the gym. I’m new to gymming, but very consistent.

I eat around 1000–1300 calories a day. Before the gym I have an espresso, a date, and a banana. During my workout I sip electrolytes because I feel drained without it.

I’m vegetarian and get around 25–30g protein a day, including a protein shake after my workout which is also my dinner sometimes.

I initially lost 5 kg, but now my weight has been completely stuck and I don’t see any visible changes. Not sure if that first drop was just water weight.

Why am I not losing more? Am I doing something wrong with food/protein/workouts?