URLs are alphanumeric, and should be disambiguous. As should most other bitmap embedded text. Keep away from using the usual Arial/Helvetica sans, Times New Roman serif, and Impact sans.
For example, some nigger decides to resize and recompress, now resized lowercase a e and g apertures are fused on the sans, resized counters become solid on the Impact sans, artifacts and subsequent artifacts destroy the serifs and stems, and the visually-complex URL is cramped and unintelligible with any 0O1Il. There is no guarantee the original image clarity will stay as intended, once it is released. Hence Mono, in Bold or Semibold. Clarity, legibility, long-term robustness.
Per my tests, Liberation Mono, Cascadia Mono, and Adobe Source Code Pro, are the best performant, in that order. Should you decide on any other Mono, do not use a Mono whose 0 (zero) looks like an uppercase O (Oh) or like a Scandinavian Ø (Oeh), and whose lowercase l (ell) looks like a number 1 (one). The old Courier style lowercase l (ell) is being deprecated.
https://github.com/liberationfonts/liberation-fonts
https://github.com/microsoft/cascadia-code