This is the solid, high-contrast version of bubble text — white letters set inside a filled black circle, using Unicode's negative circled character set.
Regular bubble text uses an outlined circle around each letter; this style uses Unicode's separate 'negative circled' block, which fills the circle solid, giving stronger contrast and a bolder, stamp-like look.
Unicode only defines the filled circle style for capital letters. To keep results visually consistent, lowercase input is automatically converted to its filled uppercase equivalent rather than mixing styles.
Because of its heavy visual weight, filled bubble text works best for short names or single words rather than long sentences.
Unicode never defined a lowercase filled-bubble set, so lowercase letters are mapped to their filled uppercase equivalent to keep the style consistent rather than mixing two different bubble styles.
Only partially — Unicode's filled circled block doesn't include a full digit set matching the letter styling, so numbers may stay in their normal form.
Yes, the regular Bubble Text Generator produces the outlined (non-filled) circle style, which supports both cases.