Parse a string with regex

I'm trying to parse the string below to get just the numbers in green (#s right before the .jpg).  I was able to do it with text to column, but I'd like to use RegEx

Unfortuately, i was getting confused by the syntax options.  Can someone offer some guidance?

Thanks!

https://photos.global.test/casual/square/5555/55552655.jpg?t=65598587595

https://photos.global.test/casual/square/5552/55528255.jpg

https://photos.global.test/casual/square/2575/25752558.jpg