Issues with some video playback

I have a Late 2013 27" iMac running Ventura 13.7.2 under OCLP 2.2. Most video playback is fine, but on occasion the playback fails - just a black screen with a lot of white blocking. This occurs when I am watching video recorded on someone's mobile device and just recently, when on a video call using Messenger. YouTube and streaming movies etc are fine.

My iMac specs are:

Processor: 3.5 GHz Quad-Core Intel Core i7

Graphics: NVIDIA GeForce GT 755M 1 GB

Memory: 32 GB 1600 MHz DDR3

All root patches are installed.

Is it my graphics card? Would a change to MacOS (e.g. Sonoma) improve things?

Many thanks!

submitted by /u/UnderstandingALot
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