Junhani, I think I figured it out. I'm running at almost 4K resolution and have Vsync, which is probably my source of lower fps. Updating snapshots did not have an effect for performance for me however.
Not experiencing this issue here.
macOS Catalina 10.15.4
6-Core i7 2.6GHz
16 GB RAM
AMD Radeon Pro 5300M 4 GB
Intel UHD Graphics 630 1536 MB
What I want to know is how were you getting 120fps before?! I have a brand new Mac and I rarely get above 40fps, and this was on previous snapshot as well.
MacBook Pro 16" 2019
MacOS 10.15.4
Intel Core i7 6-Core 2.6GHz, 16GB RAM, AMD Radeon Pro 5300M 4GB
I think this belongs under Bedrock Edition, this is the Java Edition which is on PC.