Acceptable regular expressions for Forms input validation?

The Basics

  • Nextcloud Server version: 30.0.6
  • Operating system and version: Mac OS Sequoia 15.3.2 and Ubuntu 24.04.2 LTS
  • Web server and version: unsure (I rent from Tab Digital)
  • Reverse proxy and version: unsure (see above)
  • PHP version: unsure (see above)
  • Is this the first time you’ve seen this error?: Not an error per se
  • When did this problem seem to first start?: Today
  • Installation method: unsure (see above)
  • Are you using CloudfIare, mod_security, or similar?: unsure (see above)

Summary of the issue you are facing:

I want to use regular expressions to validate forms input, but the regular expressions I use in Google Forms or LibreOffice don’t work.
Specifically, I want to validate student IDs. Each student ID is an alphanumeric string of 7 characters.
1st character: 2
2nd character: 1 or 2
3rd character: any digit 0-9
4th character: one of the following letters in uppercase: KYNSMX
5th character: any digit 0-9 or one of the following letters in uppercase: KYNSMX
6th character: any digit 0-9
7th character: any digit 0-9

Examples:
219K065
222M016
224XN33

I searched for documentation or any kind of post on this topic but couldn’t find anything.

Steps to replicate it:

I tried the following, but neither worked. The first works in Google Forms. I assume the second would work in LibreOffice, but I haven’t tested that.
[2][2][1-9][A-Z][A-Z0-9][0-9][0-9]
[2][12][1234567890][KYNSMX][1234567890KYNSMX][1234567890][1234567890]

Thanks in advance for any help you can offer.