Why can't I add more than 123 channels on the Channel Allowlist?

[SoggedFox]

I can input up to 123 channels in the Channel Allowlist textbox, but when I try to add one more channel the app fails to save the additional line, and if I paste 124 or more channels from an empty textbox the app declines to save all data. This behavior is consistent across various browsers such as Brave, Firefox, and Opera and they all share the same numerical limitation.