The same issue also for me (menu and right click). I use Linux Mint 20 Cinnamon. Thx to KetoKelo for solving. Works with hardware acceleration and Opera Beta. The same issue is present in Manjaro Cinnamon, Ubuntu Cinnamon and openSuse.
Linux Mint 20 Cinnamon
System: Kernel: 5.4.0-26-generic x86_64 bits: 64 compiler: gcc v: 9.3.0 Desktop: Cinnamon 4.6.6
wm: muffin dm: LightDM Distro: Linux Mint 20 Ulyana base: Ubuntu 20.04 focal
Machine: Type: Desktop Mobo: ASUSTeK model: PRIME X370-PRO v: Rev X.0x serial: <filter>
UEFI: American Megatrends v: 4024 date: 09/07/2018
CPU: Topology: 8-Core model: AMD Ryzen 7 1700X bits: 64 type: MT MCP arch: Zen rev: 1
L2 cache: 4096 KiB
flags: avx avx2 lm nx pae sse sse2 sse3 sse4_1 sse4_2 sse4a ssse3 svm bogomips: 108581
Speed: 1882 MHz min/max: 2200/3400 MHz Core speeds (MHz): 1: 1882 2: 1892 3: 2674
4: 2255 5: 1717 6: 1879 7: 1711 8: 1705 9: 2033 10: 1888 11: 1882 12: 1886 13: 1882
14: 1891 15: 2465 16: 2654
Graphics: Device-1: NVIDIA GP107 [GeForce GTX 1050 Ti] vendor: ASUSTeK driver: nouveau v: kernel
bus ID: 09:00.0 chip ID: 10de:1c82
Display: x11 server: X.Org 1.20.8 driver: modesetting unloaded: fbdev,vesa
resolution: 1920x1080~60Hz
OpenGL: renderer: NV137 v: 4.3 Mesa 20.0.4 direct render: Yes