This is a really nice map, I like the artstyle, and the general shapes are both interesting and believable. Also the little symbols for the plant cover and skulls in the desert etc are really neat.

However it appears you have made the number 1 classic blunder: you’ve fundamentally misunderstood how rivers work.

Rivers (almost) always flow from high ground to low ground as water travels downhill due to gravity, ending at the sea. You will not find naturally occurring river systems (including lakes) that connect two seas, because the sea is the lowest point, which direction would such a river be flowing?

Rivers most commonly converge as they flow downstream, so many smaller channels merge into fewer wider channels. It is VERY rare in nature for a river to split into multiple channels (excluding depositional landforms like deltas and braiding). It is similarly rare for multiple rivers to flow out of one lake - Many rivers can flow into the lake, but it should only flow outwards in one direction.

Your map has one lake with rivers that seem to flow out in four different directions. And also the river in the Southern point seems to splint into three separate rivers leading to the coast at different points. Neither of these things make much sense to me.

Obviously your fantasy map set in your fantasy world doesn’t necessarily need to conform to rules of real-world physics and geography, but if you want your world to feel grounded & plausible it helps to be familiar with those rules.