3 of my All-on-4 implants were rejected 4 weeks after surgery. Will it happen to the rest? Will the replaced implants be OK?

It’s a simplistic answer, and likely an incorrect one as well,  to say that you shouldn’t have had implants placed..... there’s a reason that you considered the All-on-4 in the first place, likely your teeth were in poor condition and you were looking for full arch options. The All-on-4, when done correctly, is far and away the best option to replace a full arch of teeth.
While your autoimmune condition may have played a part in the failure of these implants, it’s impossible to truly determine the cause of failure without seeing the full picture.
The success rate of the All-on-4 is as a matter of routine in the range of 97-99%. This is verifiable through studies that date back to 1990. Your autoimmune condition may have lowered the success rate somewhat, but I’d still expect a success rate in the range of >90%.
There are multiple reasons why implants fail as part of the All-on-4 procedure and it almost always points back to the provider completing the procedure. I wish I could say that your experience is uncommmon, but as the All-on-4 becomes more mainstream, many dentists and “specialists” are jumping into providing treatment with both feet without having a true understanding of what they’re doing.... As an Oral Surgeon, I am seeing more and more salvage cases; these are cases that were initially completed by another provider and are now needing to be redone.
While I do not want to make accusations without having the full picture, you may want to consider getting a 2nd opinion in an effort to better understand what happened, and to avoid a repeat occurrence.