I tried different font settings in the font settings and it didn’t improve much (font hinting, anti aliasing, custom DPI settings, different font size)
The font is the default one which is Ubuntu Regular with font size set to 10
Sub pixel order is set properly to RGB Linux Mint xfce
Even when running windows in a virtual machine, the font rendering in it is miles ahead of what I got on my Linux setup!!!
On KDE plasma the fractional scaling also plays a role in text rendering. Then there’s also the “Legacy Application Scaling” for X11 apps on the Wayland session.
I have decided to switch to OpenSUSE which uses KDE by default so let’s see and if this old laptop can’t handle it then will switch to Lbuntu as LXQt is its main and only variant available unlike mint