Hey! Having same thing here!
Bought an Executive 16 one month ago and I have 90hz only in 2560x1600 resolution. 
For anything else like FHD for example, 48 hz only, kind of eyes killer. So, is it a linux mint thing or hardware thing? It sound very weird having a screen at only 48 hz in 2023 in FHD isn't it?

Did you try some various live systems with different DEs to test it out?

I would be especially interested in seeing how Plasma on a newer kernel and with the newest packages like on Manjaro is coping with that.

not really, actually I was thinking seriously to change the os to windows... since I bought it I had nothing more than problems with linux... NOt my first time with the OS, I have been playing with distros since ever but I could neer have a good and stable for production. Since I work with 3D animation my only chance working in a linux environment was virtualizing it. But now with all this regarding refresh rate, plus if I connect a second monitor the performance of the desktop slows down adn bla bla bah, mmm not being a good deal keep trying

I'm currently using a 10 years old Alienware (using it from the beginning) and it's working quite well on Linux. The only issues I noticed are:

- proprietary, dedicated sound card without drivers on Linux, so current, generic sound drivers are sometimes not working, solution is to do a hard reset, but it happens sporadically, once a week or rarer, so this isn't anything big

- depending on dGPU drivers quality, suspend sometimes work or doesn't work, currently it works

- BIOS updates must be done from Windows

- RGB keyboard setting must be done from Windows

The rest works. I'm using hybrid session in KDE with Wayland, no bigger problems, dGPU works when needed, multimonitor works with optimus-manager working, gaming too. My OS is Manjaro KDE (the same install from 10 years).

Because the battery is declining (this is already a third one), and gaming performance is low in newer games (still, I was able to play and finish BG3), this is the time to look around to buy a new laptop, hence my interest in Hero model.

If not the frequency issue, I would be sure. I intend to use it for work outside, in the summer, so with high heat and high sun, so the brightness must be set to 100%. To spare battery, I planned to use 1920x1080 and 60Hz, which I have now - I'm happy with it. Heroe's monitor is brighter, which is a plus, but again, the high refresh rate worries me, especially that there were some issues regarding various refresh rates in multimonitor setup. This was recently fixed, but issues with the second monitor slowing down are not encouraging, especially that it happens to many people.

I suspect that my current laptop's dGPU is so old, that it doesn't have issues of modern ones, so on one side it is an upgrade, on the other, it may be a downgrade.

Anyway, I'm looking for some info from Slimbook users. Is my refresh rare a valid worry or not? What are your experiences?