Help needed with RegEx redirections not working

Hi! I’m experiencing an issue where RegEx redirections aren’t working. I had one written like this:

Source: /some-text-goes-here/
Destination: /{URL of my site}/

When I visited the URL to redirect, I get a 404 “not found” page instead. So, I tested my source expression and found it was incorrect. Since I didn’t “escape” the forward slashes, the expression was “bad”. So, I added escapes to the forward slashes and my expression started working in online RegEx test sites, like regex101.com. However, the redirection still didn’t work.

So this is my question: where can I find documentation on the RegEx syntax the RankMath Redirection Manager expects for RegEx redirection expressions? I’ve seen other support tickets where the corrected RegEx syntax, for a given expression, was provided but there was no reference to a “syntax guide” of sorts. Are PCRE expressions expected vs JavaScript expressions?

I resolved my immediate issue by changing from “RegEx” to “Contains” and now the redirection works as expected.

Thanks in advance!