So far I have just noticed this in version 1.16.1 but I am sure it is in older versions as well. When landing on a block next to either a source block or flowing lava, you can get lava particles as if you landed in a block of lava if you are pretty close to it. The block has to be above the lava, or on the same level as it.  For example, if I was to land on a block of Netherrack and look downwards, I would see particles resembling the block of Netherrack. Similar cases for every block. If you land on any block next to lava and look down you will see bright orange particles, as if you landed in the lava. I don't know if this is intentional or not.