aestheticsymbols
Use in a combo

Lower-left quadrant arc copy & paste

◟ is lower-left quadrant arc, a plain-text Unicode symbol from the Geometric Shapes block. On Aesthetic Symbols it lives in the borders & shapes collection. As plain text it takes on the font and colour of wherever you paste it — a bio, a username, a caption or a stream title.

Unicode
U+25DF
HTML entity
◟
CSS content
\25DF
JavaScript
\u{25DF}
UTF-8 bytes
E2 97 9F
Made of

U+25DF ◟ · Geometric Shapes

Will it show up? · Long-established text symbols

Plain-text characters from blocks that mainstream desktop and mobile fonts have covered for years. These are the safe ones.

Worked out from how each character is encoded, not from a test on a real device.