Low frame rate while exporting videos using quicktime

Hello. I have recently updated to MacOS Sequoia 15.0.1. I run a 2019 16 inch Macbook Pro 2.6Ghz 6-core Intel Core i7 with 16 GB of DDR4 memory.

After the update, my video exports in quicktime done at 4k resolution, Greater Compatibility (H.264) mode, run a paltry framerate of 15fps. This issue was not present before sequoia update.

Could I please be guided to a solution/resolution of this issue ?

Thanks in advance.