Macbook Pro 2016 - Graphics card crashing

My Macbook Pro 2016 on 10.15.7 had its battery replaced 4 weeks ago by MyMac (Authorised Service Centre). I reinstalled MacOS within two days of getting it back, but now I have been having a host of issues.

Previous tasks of screen sharing while on a Zoom call, rendering video or looking at 3D content in a web browser that I do for work over the 4 years. Now have the computer crashing and restarting.

Any thoughts on what the solution is? MyMac told me to install MacOS again....

Thank you