Token lifetime
The default lifetime of an access token is variable. When issued, the Microsoft identity platform assigns a random value ranging between 60-90 minutes (75 minutes on average) as the default lifetime of an access token. The variation improves service resilience by spreading access token demand over a time, which prevents hourly spikes in traffic to Microsoft Entra ID.
Access tokens in the Microsoft identity platform - Microsoft identity platform | Microsoft Learn
It looks like there is a preview feature to configure the token lifetime (I have not tried)
Configurable token lifetimes - Microsoft identity platform | Microsoft Learn