I'm not a doctor, but I'm well read on biology, certainly more than most non-professionals.

And the issue there is that an antibody with only the FC segment will end up causing long term health issues and would actually be toxic to your body long term

The mRNA "vaccine" or viral vector is an instruction to your cells to produce the SARS-CoV 2 spike protein, and not the whole virus. The envelope, membrane, and RNA Genome are not transcribed. Therefore the only immune response generated can be for that part of the virus.

This can improve immune efficacy in reducing infection of cells, since the spike is the "key" that attaches to ACE2 enzymes that allows the virus RNA into target cells (lungs, kidneys, heart, etc.). The only problem is that where the immune response fails (which granted, should be far less often than without spike protein anti-bodies) and a virus does infect a cell then the virus will still reproduce as normal within the affected cell. The subsequent viral load of that infection will be lesser still since in order for these newly reproduced viruses to infect more cells, they will still be targeted by the spike protein anti-bodies from the mRNA therapy. This is the theory anyways.

But to answer your question, the reality is that there is no long term data and the long term consequences are not known. The doctor makes great points in the linked video about how we have no good idea for how long the mRNA continues to transcribe, nor any good idea for how long the anti-bodies will last.

It's because of that lack of data that I'm opposed to these mRNA therapies when already established medicines and therapies exist for most healthy people. mRNA vaccine's hypothetical efficacy is scientifically sound, but they are still not sufficiently experimentally tested. I just know enough to point out bad science like the user above claiming it will alter your own mRNA or DNA.