I'm having the same issue. I load a RTX resource pack over 128 texture size I get a "Resource pack Fallback, Low memory" error message. Afterwards texture quality looks awful. I'm using Realsource pack RTX and have tried it with several other high res packs and it still happens. I know I have plenty of memory because it only using 3% of my NVIDIA GeForce RTX graphics card and 21% of the 32 GB of ram i have installed on my computer so it shouldn't be a hardware limitation on my end. I've been having this issue since RTX was initially released.
I'm having the same issue. I load a RTX resource pack over 128 texture size I get a "Resource pack Fallback, Low memory" error message. Afterwards texture quality looks awful. I'm using Realsource pack RTX and have tried it with several other high res packs and it still happens. I know I have plenty of memory because it only using 3% of my NVIDIA GeForce RTX graphics card and 21% of the 32 GB of ram i have installed on my computer so it shouldn't be a hardware limitation on my end. I've been having this issue since RTX was initially released.