If 0.999... equals 1, what about 0.999...8?

In ordinary decimal notation, there is no decimal like $$0.999\ldots 8.$$ The dots mean the 9s continue without a final position. If there is no final position, there is nowhere to put the 8. That is different from a long finite decimal such as $$0.999998.$$ Finite decimals can have a last digit. Infinite repeating decimals do not. So $$0.999\ldots=1$$ is not saying "there is a tiny 8 or 1 at the end." It is saying the infinite decimal is defined as the limit of $$0.9,\ 0.99,\ 0.999,\ldots$$ and that limit is exactly 1.