When required people just omit the diacritic signs and replace the letter with regular ASCII letter, so for example: ż->z, ł-l, ó->o, etc.
When used in (computer) writing this is very readable, but no one would do this with handwriting, I think most common cases nowadays would be SMS messages (especially on dump phones) or some weird displays that are unable to properly render diacritic letters.
When used in (computer) writing this is very readable, but no one would do this with handwriting, I think most common cases nowadays would be SMS messages (especially on dump phones) or some weird displays that are unable to properly render diacritic letters.