You have done a pretty good job at detailing your problem, except for my quote. You really need to be more specific about what you’ve tested.
Have you disibled MAC Address randomization (if not search for how to do that). I would also disable IPv6.
I don’t happen to be at home to refer to my network notes. However, if I recall correctly this is one of Realtek’s old dogs from their lineup. I don’t have anything against Realtek, but like most manufacturers they have good adapters and bad. This is rather one of their poorest wifi adapters. Personaly I’d think about a replacent because even if you get it working, it’s performance is generally very poor.
Replacing an internal wifi adapter in a desktop is rather easy, so that would be a fairly cheap and easy fix IMO. You could use an internal add in card or a USB dongle. You will get far better performance from a relatively inexpensive replacement than you’ll ever see out of your current model.
I usually don’t give this advice very often, but in your adapter’s case it’s often just not worth the effort to try and get it working (especially on a desktop computer).
As this is a desktop is Ethernet an option. If running cables is a no go then I might mention that a powerline networking setup would be a vast improvement over wifi. The nice thing about using a powerline setup is that they do not require special drivers. So you are pretty much guaranteed compatability with Linux.
A powerline network setup is definitely more expensive than buying a cheap wifi replacement, however your speed and reliabilty will be far superior to Wifi. Just something to think about if you don’t want driver issues on Linux. You can search online for details about powerline networking if you are unfamiliar with it. Only pay attention to new reports on powerline networking as the old technology when it first came out was not very good. Recent powerline systems are excellent IMO.
Welcome to Garuda BTW.