Not sure if this applies to your situation but around the same time I had my first couple of episodes of Afib, I was also experiencing nearly constant fatigue, which I attributed to possible long Covid and /or the 50 mg of Metoprolol prescribed by my cardiologist. When I met with an EP to discuss getting an ablation, he told me about sleep apnea, which is associated with Afib, and according to him, it is very under diagnosed. At his advice I had a home sleep study, which revealed moderate sleep apnea, about 35 disturbances per night. So, I started using a CPAP machine, and soon thereafter, my energy level improved. My oxygen levels while sleeping often dipped below 89 prior to using a CPAP, and with the CPAP machine are always 94 and above during the night (Apple Watch). I still take 25 mg of Metoprolol, but it doesn't seem to cause fatigue.