Screen taring in Ubuntu when connected to the GIGABYTE RTX 4090 through HDMI... but only sometimes?

The title says it all.
Screen taring occurs when the monitor is hooked up to one of the HDMI ports of the graphics card, but only sometimes.
But as a videographer, screen taring occurring once is already enough.
I haven’t tested the full capabilities of the graphics card yet as it already occurs when watching a movie using VLC media player.
Sometimes when I restart the computer, the screen taring seems to be gone.
But who knows when it occurs again.
The tare is horizontal, roughly in the middle of the screen. Perhaps, slightly above the middle.
I would very much like to get rid of it.
If someone can help me, that would be great.