Buffett stopped all buybacks around the $470 per B mark.

FWIW, many of us believe he stopped before that, and that those transactions were price-insensitive purchases from long time shareholders. I would be a bit hesitant to read too much into those.
To be specific, there has never been a buyback anywhere near $470/B, so far the highest monthly average price paid has been $357.22. Only A shares have been repurchased since November 2023.

I personally don't believe any buybacks have been done for economic reasons above 1.5 times known book. Of course that might change, or I might be wrong. FWIW, the highest paid for B shares so far has been 1.48.

This tea-leaf-reading about what can be inferred from specific buybacks has nothing to do with the simpler observations that
* real value per share had done very nicely, and has kept rising through thick and thin, and will presumably continue to do so for some time to come, and
* valuation levels are higher than they have been in the last 17 years, so the price return from here will be poor for a while unless these valuation levels last (unlikely in the extreme, but always possible).

Jim