are you using the replaceAll function? https://docs.mendix.com/refguide/string-function-calls/#13-replaceall
if so, take a look at the documentation of that function, this function is using a regex as a parameter :
"The regular expression to match; if you want to search for a literal string, enclose it between
\E (for example,
\QPaul S. Mueller\E will search for the string
Paul S. Mueller, without interpreting the dot as a wildcard)"