As someone who has been following this games development since the Kickstarter, I can only wish you the best going forward with your current condition.
I'd say most people are happy to wait for as long as it takes for a great product to be made, so please don't be too hard on yourself over something that is frustratingly beyond your control (I had long COVID myself, as mentioned in a previous comment, though not quite as long as yours). Work at a rate that gives you the results you want.
Also, remember to take regular opportunities to chill and turn your brain to less intense, more relaxing activities so it can reset for the next time you tackle the project.
Whatever happens, I'll still be looking forward to each update leading to the game's release. :)