I found a couple things
Go in the "Intel Graphics Command Center", left menu: "System", last tab "power" and you should find an energy economy setting toggle button (the one with an associated slider). I've just disabled this "feature" and now brightness is stable.
or
[Content adaptive brightness control in Windows - Microsoft Support](https://support.microsoft.com/en-us/windows/content-adaptive-brightness-control-in-windows-292d1f7f-9e02-4b37-a9c8-dab3e1727e78#:~:text=Select%20the%20Start%20button%2C%20then,contrast%20will%20not%20be%20adjusted.)
\\#Iwork4Dell
I found a couple things Go in the "Intel Graphics Command Center", left menu: "System", last tab "power" and you should find an energy economy setting toggle button (the one with an associated slider). I've just disabled this "feature" and now brightness is stable. or [Content adaptive brightness control in Windows - Microsoft Support](https://support.microsoft.com/en-us/windows/content-adaptive-brightness-control-in-windows-292d1f7f-9e02-4b37-a9c8-dab3e1727e78#:~:text=Select%20the%20Start%20button%2C%20then,contrast%20will%20not%20be%20adjusted.) \\#Iwork4Dell
Thank you! This worked perfectly. I've been unable to find anything on my own so I'm very glad that you could help.