There is nothing that’s incompatible. I don’t update my plugin with a new tested value every time WordPress releases a new version, but it’s still working just fine.
I’m not familiar with Brevo and whatever plugin you use to connect to it. But, it’s possible they made an update recently that is rejecting emails from my plugin for some reason.
If reminders are being sent, but the clear and reminder emails are not, then my best guess is that you maybe have a “CC email” set in my plugin in the Email settings, which is used to send a CC copy for reminders and clear emails. If so, then it’s possible that Brevo, or your SMTP plugin that connects to Brevo, suddenly doesn’t like the CC email format my plugin uses. There is another setting at the bottom of the emails settings page in my plugin that you can check “Separate CC/BCC to individual TO emails?”. If you check that option, instead of using CC or BCC to send to the additional recipients in one email, my plugin will send a separate email to each of the addresses. Try that to see if it fixes the issue. If it does, then maybe notify whoever makes your SMTP plugin that their plugin is now rejecting CC/BCC emails that are formatted according to the original specs of WordPress outline for their own wp_mail function, since that is how I format my email headers and info.
If that’s not the issue, then check to see if your SMTP plugin has a log file you can check, and maybe it will give a reason why the email wasn’t sent. Or, if there’s nothing in your SMTP plugin, or its log file, you can see if there is any kind of log for your Brevo account that can shed some light on what’s going on.
