Bro you are coming from an Ender. Throw out half the stuff you do as habit from that machine. Lets adjust one thing at a time-
Ringing is acceleration that is too strong for your print speeds. What I mean by that is if you have manually slowed down the print speeds but left the accelerations at default then that could be the ringing issue. You do not need to slow this printer down almost ever. Only with very specific scenarios should you need to mess with every single one of your print speeds. I have only ever had to do this with transparent petg on thin walls. You are printing a very basic part. You are trying too hard on this regard. It’s not an ender and will never be one. Default all your speeds or even your profile. I only ever got ringing when slowing my prints down to Ender-like speeds.
Filament- Is this filament any good? Do you stand by it? I don’t know it so I am just asking.
Banding- This is fan speeds changing. There are two types of banding, the kind that happens at a layer which starts and/or ends a x/y hole like you have there and the other is banding of several layers in a specific section of the print every time, all the time. To resolve this in Orca or BLS you need to go to the filament config and understand how the algorithm works under fan speed. It uses layer time to dictate fan speed. The slicer believes that a shorter layer time requires faster cooling so that the layer has set before the next one is dropped. This makes sense…to a point. Sometimes it just gets it wrong for your particular combination of filament and model design, especially petg. To get a consistent finish look at the top right box after slicing the model. Check the layers that exhibit the issue here and note their numbers. Check layer time, layer speed, and fan speed. Most likely you will see a DIRECT correlation in graphically speaking between one or more of these 3 characteristics and the banding. The slicer will literally show you the banding. Once you find the issue-for example fan speed rising gradually in a layer just before a bridge. Adjust those settings only. To best see what I mean and how you can resolve it without wasting too much filament, model your self a ring about 20mm in height and only 2 or 3 walls thick. Put a hole in the x/y in the middle of the height. Export and slice it. Print with a default profile and watch the banding happen. Now adjust it till it stops. The adjustment to make is this- in the fan speed calculation make the layer times extreme so that the slicer is forced to use the same fan speed for the entire outer wall. After making the adjustments re-slice and check fan speeds to ensure it worked. You should see one solid color throughout the sliced profile with the exception of overhangs or bridges. Use layer times in the conifg that are higher and lower than what the slicer calculates on the default slice. I am attaching photos of a before and after these adjustments. You will see the slicer actually shows you where the banding will occur. I have fought and conquered this problem myself. It is not the printer and its not the filament typically. Its a slicing algorthim that works only 98% of the time. For reference my pics are from a petg profile.
Notice in the re-configured profile the banding still shows in layer time- thats obviously expected as we have not changed the actual layer time. But under fan speed now the entire part is the same color save for the overhangs. Do this and your parts will come out PERFECT EVERY TIME.