Macbook Pro high CPU utilization when external monitor plugged in and making video calls

I have a Macbook Pro (Retina, 15'', Mid late) with following specs:

• 2.5 GHz Intel Core i7 quad core
• 16 GB 1600 MHz DDR3
• AMD Radeon R9 M370X 2 GB
• Intel Iris Pro 1536 MB
• macOS 11.3.1

I have an external monitor plugged in (mini display port to HDMI) all time with ~7% CPU average (Firefox, Slack, Telegram, WhatsApp) but when I join to a meeting using web browser (Google Meet), or using dedicated app (Zoom, WhatsApp, Chime) my CPU utilization goes to 100% freezing all my system. If i unplugged the monitor my CPU utilization return to normality.

I need help! In home office times, this is a pain in the neck.