I use these resource packs together for month and never experienced things like this red triangle before, but when i updated the game to 1.16.100 and enabled these 3 resource packs, a red cursor popped up on my screen. (The red cursor was visible in previous betas without resource packs. These resource packs are the following:
1. Java aspect+ ( http://download2008.mediafire.com/u7qy8j5u4ceg/kyu26kthw9uxtc5/JavaAspects%2B%284.5.0%29.mcpack )
2. Java UI ( http://download602.mediafire.com/aa7zh7zxjadg/aa6st9zn4iq1efy/VDX+-+Java+UI+v1.10.mcpack )
3. Fog remover ( http://download807.mediafire.com/0yj93onesddg/ponl9mpvecvz2ye/FogRemover.mcpack )