I use a format I call id25, with takes a time-sorted UUIDv7, and represents its 128 bits as 25 chars from a Base 35 alphabet which has 0-9, a-k, m-z.

Since I could drop one char from Base 36, and still store 128 bits, I decided to drop the "l", to reduce ambiguity with "1". And since I used lower case letters, "o" and "0" look quite different.