[teddyh]

Having all those TXT records at the domain apex like that makes the TXT query reply huge, which affects, for instance, every mail recipient who merely wants to check the SPF record. This is a bad pattern to follow.

[Bender]

It's also used in DNS DDoS amplification attacks. Spoofed UDP requests to domains that have a large number of TXT records are used to slam other sites.

[inigyou]

The better pattern is to use an underscore prefix like _discord-verification.domain.com

If your site allows user-created subdomains it shouldn't allow leading underscore. This is reserved somehow.