After a couple years of fatigue, I found the solution is to increase nitric oxide production that improves oxygen going to the tissues. Our nitric oxide production decreases as we age. I would suggest researching nitric oxide production foods and supplements.
I take citrulline and L-arginine with vitamin C each morning. That is major in my getting back to normal. If you are on meds, check to see if there is an interaction. In most cases, there is no interaction, but it is best to be cautious.
I will give a couple references from my journal:

Nitric oxide decreased levels may cause chronic fatigue. Low nitric oxide levels can decrease your body’s natural energy at the cellular level. This is a result of reduced circulation, reducing the delivery of oxygen and nutrients that your body needs.
https://www.medicinenet.com/what_does_nitric_oxide_do_to_your_body/article.htm
The mechanism of action that leads to the state of fatigue, or disabling exhaustion, linked to Long Covid which affects 1 in 3 people who are victims of the Sars-CoV-2 infection has been discovered: it is triggered by a deficit of arginine, an amino acid naturally produced by the body.
https://www.coronaheadsup.com/health/long-covid/long-covid-fatigue-caused-by-an-arginine-deficiency/
Boosting NO production 1. Have RAW greens at every meal or at least daily 2. Cooking and dehydrating destroy NO-building capacity 3. Accompany greens with a source of Vitamin C 4. Consume foods high in polyphenol antioxidants like dark colored fruit, (berries), red wine or grapes, and dark chocolate (65% cacao or more) 5. Include exercise in your daily routine, 30 minutes is recommended 6. Fish oil and other unsaturated oils boost NO production {or fatty fish twice a week instead of fish oil] 7. Refrain from using mouthwash since it can decrease NO production by at least 1/3
https://extension.oregonstate.edu/sites/default/files/documents/8836/asay-no-disease-handout.pdf
Note: High salt and high sugar can deplete nitric oxide production and should be avoided. Plan on a couple of months of diet and supplement adjustments to get to "normal", but it is worth the journey.
Good luck!