First update all of your Lenovo Laptop drivers from Lenovo's Support download page: https://pcsupport.lenovo.com/us/en/products/laptops-and-netbooks/thinkbook-series/thinkbook-16-g4-ar...
Input your Laptop Serial number in the above link to verify the correct download page for your laptop.
Download Lenovo's OEM AMD Graphics and Chipset drivers and update your BIOS if it is older than the one shown.
From your Laptop Manual concerning your Laptop Screen resolutions:
Not sure if your laptop has the 1920 x 1200 Resolution or the 2k resolution of 2560 x 1600
On YouTube turn off "Annotations" under the Video's Settings, which can place extra stress on your GPU card causing it to crash.
Also run YouTube at 2k or lower Resolution for your laptop unless you have an external Monitor connected with a higher resolution than 2k.