I've been having this since Dec. 2020. The problem I have with diagnosing it as Long Covid is the cause. My breathing issue started Dec. 14, 2020. I went to a dr. and was diagnosed with anxiety and prescribed Buspirone. I had only been taking it five days and did not get tested for covid, when I started getting symptoms of fever, sore throat, etc. Tested positive. If I had tested when the breathing started I would have a better assessment of whether it was Covid, anxiety, or just a breathing pattern disorder. I'm currently on Prozac 40 mg daily and I had a Zoom series of sessions with a breathing pattern disorder physiologist out of the UK. I practice the breathing twice a day. Every day since the onset I have written on a calendar whether it was "good" or "bad". That was just so I could see if I was improving. I have improved, quite a lot. But overall, it's recovery/relapse and about the same every month. In June I had 20 good days and 10 bad. That's pretty consistent lately but it's slowly getting better.
I still have two cups of coffee in the morning but now I do 1/2 caffeine, 1/2 decaf.

This Power Breathe was recommended by the breathing pattern disorder physiologist. I highly recommend! It strengthens your diaphragm to breathe through it rather than upper chest. And no mouth breathing!
https://www.amazon.com/POWERbreathe-Breathing-Strengthen-Inspiratory-Resistance/dp/B000NVLEHY/ref=asc_df_B000NVLEHY/?tag=hyprod-20&linkCode=df0&hvadid=309837891290&hvpos=&hvnetw=g&hvrand=7121682979565089997&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9025239&hvtargid=pla-406644660455&psc=1&tag=&ref=&adgrpid=63334408682&hvpone=&hvptwo=&hvadid=309837891290&hvpos=&hvnetw=g&hvrand=7121682979565089997&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9025239&hvtargid=pla-406644660455