A real, complete Unicode block — not an approximation#
Unlike upside-down text, which has to approximate letters with unrelated lookalike characters, bubble text comes from a genuinely complete Unicode block called Enclosed Alphanumerics, purpose-built to contain a circled version of every letter A-Z (both cases) and every digit 0-9. That completeness means every letter and number in your input has a real, correct circled counterpart — nothing is approximated or substituted.
What does not get circled, and why#
Only letters and digits have circled equivalents in this Unicode block — punctuation, spaces, and accented or non-Latin characters do not, since the block was never extended to cover them. Those characters pass through unchanged rather than being dropped or substituted with something misleading, so the output stays legible even for input with punctuation mixed in.
Font coverage still applies, same as any less-common Unicode block#
These are valid, standard Unicode characters, but — like most characters outside the basic Latin alphabet — not every font on every device includes a glyph for each one. A bubble-text bio that displays perfectly on one phone can show empty boxes on an older device or a font with narrower Unicode coverage. This is a font-support limitation shared by every tool that generates this style, not something specific to this one.