Best way to prevent odd characters?

Question
1

Hello, Several times in the past my site has essentially crashed as a result of users spamming odd symbols such as “𒐫” over and over into multiline input boxes, making the database for these objects unreachable, and forcing me to roll back portions of the database. I am now looking into ways to prevent text like this, initially assuming Regex to be the best option; though I do not want to ban normal symbols from input boxes such as currency symbols, which there are dozens of. Was wondering if anyone knows a better solution than regex for this issue? Thank you!