Quotas are set at different levels for users of consumer accounts (such as gmail.com) and different G Suite/Google Workspace editions.
Daily quotas are refreshed at the end of a 24-hour window; the exact time of this refresh, however, varies between users.
Here’s a reference for the email sending quota limit using Apps Script:
Email API Quota Limit
[References]
https://developers.google.com/apps-script/guides/services/quotas
https://support.google.com/a/answer/166852?hl=en
You can also check your daily email quota limit using getRemainingDailyQuota method in MailApp Class:
var emailQuotaRemaining = MailApp.getRemainingDailyQuota();
Logger.log("Remaining email quota: " + emailQuotaRemaining);
If you're already using a paid subscription and still met the email quota limit, then it would be best for you to look for an email campaign services that will allow you to send more than the specified email quota limit provided by Google Workspace