As you Exchange and Exchange Online have a mailbox policy parameter to allow reporting junk email (ReportJunkEmailEnabled – see https://learn.microsoft.com/en-us/powershell/module/exchange/set-owamailboxpolicy?view=exchange-ps#-reportjunkemailenabled).
In addition of this parameter, you also have the Report message add-in (see https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/enable-the-report-message-add-in?view=o365-worldwide) which allows to report junk/phishing emails or false positive.
Well, starting November 25, 2022 (expected to be completed by December 10, 2022), the ReportJunkEmailEnabled mailbox policy parameter is being deprecated and replaced with the add-in and user reported settings page in the Security portal (Policies & rules\Threat policies\User submissions)
If you did not had the user reported settings configured, it is time to do so.