They definitely have some piercing highs as you can see from the graph of the 32 ohm version - https://forum.headphones.com/t/beyerdynamic-dt-990-premium-official-thread/18422

You may be experiencing this "underwater" effect due to a bit of recessed midrange and raised lower midrange. The DT880 have less treble spikes, but if you want more treble energy the DT990 Pro 250 ohm has that (you can see so in the link)