Reminds me of Babbage making allowance for meter.

"""

    ... it is said that he [Babbage] sent the following letter to Alfred, Lord Tennyson about a couplet in "The Vision of Sin":

         Every minute dies a man,
         Every minute one is born

    I need hardly point out to you that this calculation would tend to keep the sum total of the world's population in a state of perpetual equipoise, whereas it is a well-known fact that the said sum total is constantly on the increase. I would therefore take the liberty of suggesting that in the next edition of your excellent poem the erroneous calculation to which I refer should be corrected as follows:

         Every minute dies a man,
         And one and a sixteenth is born

    I may add that the exact figures are 1.167, but something must, of course, be conceded to the laws of metre.

    Charles Babbage and his Calculating Engines

Not from one token, from one embedding. Text contains a low amount of information: it is possible to compress a few token embeddings into a single tiken embedding.

The how is variable. The calm paper seems to have used a MLP to compress from and ND input (N embeddings of size D) into a single D embedding and other for decompress them back

The mechanism would be prediction (learnt during training), not decompression.

It's the same as LLMs being able to "decode" Base64, or work with sub-word tokens for that matter, it just learns to predict that:

<compressed representation> will be followed by (or preceded by) <decompressed representation>, or vice versa.