In theory, I think it’s okay. The anchored spike protein probably gets degraded after a few days as part of the body’s day-to-day metabolism. This is consistent with animal studies showing that the vaccine-induced expression of spike proteins only lasts for a few days.

This also makes sense considering that mRNA is incredibly fragile and doesn't replicate. So, once the mRNA gets used up, there won’t be any more translation and production of spike proteins.

One consequence of anchored spike proteins, as far as I know, is the stimulation of the immune system. Antigen-presenting cells (APCs) like dendritic cells will recognize the spike protein antigen on the cell surface and present this antigen to the B-cells and T-cells (of the adaptive immune system) to mount an immune response and generate immune memory. I hope that helps a bit, but let me know if anything else is unclear.