I have tried the default and lts kernel of cachyos. I have tried disabling powersave mode and added the line below to /etc/NetworkManager/conf.d/wifi-powersave.conf:
[connection]
wifi.powersave = 2

Then I tried adding the lines below to /etc/modprobe.d/iwlwifi.conf:
options iwlwifi power_save=0
options iwlwifi swcrypto=1
options iwlwifi 11n_disable=8

Nothing worked. Let me describe the issue: The wifi speed sometimes goes up to 80-90mbps (which is what I expect), but then it goes down to very slow speeds (under 10mbps). It’s unstable and I can’t properly play online games, browse internet, download things etc.

There’s another thread about this, but it’s unresolved.

Switch NetworkManager’s Wi-Fi backend to iwd
This is one of the most reported fixes for AX200 dropouts and instability on Arch-based distros.

Install iwd if not present:
sudo pacman -S iwd
Edit /etc/NetworkManager/conf.d/wifi_backend.conf:

[device]
wifi.backend=iwd

Restart network manager:

sudo systemctl restart NetworkManager

reconnect to network

Many users (including on Framework laptops and desktops with AX200) report this immediately stabilizes speeds and prevents fluctuations

I didn’t change the /etc/NetworkManager/conf.d/wifi-powersave.confand it has this value:
[connection]
wifi.powersave = 2

And changed /etc/modprobe.d/iwlwifi.conf to:
options iwlwifi power_save=0 11n_disable=8

Then rebuild initramfs and reboot:

sudo mkinitcpio -P
sudo reboot

I think it somewhat solved the issue or at least something else did (maybe some update or something else) and now I get better and more stable speeds (still inferior to speed in windows, but at least acceptable)