The most commonly reported breathing problem is "abnormal breathing", which can 100% be caused anxiety/stress/etc, especially when COVID hysteria is driving hypochondria.
There is no compelling evidence that the correlation between these self-reported symptoms, and having a COVID infection months prior, is due damage caused by the COVID infection, and not due to any number of other confounding factors. There have been no rigorous studies, i.e. large, randomized and controlled studies, showing this.
Notice how extreme rigor is demanded for the ivermectin studies but then really just mere correlation is enough to draw scare mongering conclusions about covid.
Also, the theory simply doesn't make sense, given the vast majority of COVID cases are mild, with no evidence of the kind of acute lung damage that can lead to long-term complications affecting breathing. If lung damage from COVID was really that pervasive, we would know about it, both from the acute symptoms, and from imaging scans.
Low energy
Headaches
Upset stomach, including diarrhea, constipation, and nausea
Aches, pains, and tense muscles
Chest pain and rapid heartbeat
Insomnia
Frequent colds and infections
Loss of sexual desire and/or ability
Nervousness and shaking, ringing in the ear, cold or sweaty hands and feet
Dry mouth and difficulty swallowing
Clenched jaw and grinding teeth
Sounds like all of the physical symptoms of so-called long-COVID.