When you open the Voice Memos app with both Mobile Data and Wi-Fi turned off, you may receive a pop-up message informing you that Cellular Data is needs to be enabled. This alert appears because the Voice Memos app may attempt to access the internet—for example, to sync or back up your recordings to iCloud or to refresh your library across devices. If you’ve enabled iCloud syncing for Voice Memos in the past, this message serves as a reminder that data usage is occurring in the background. See the Pic 1 below
Similarly, if Location-Based Naming is enabled within the app’s settings, you might see another message indicating that turning on Wi-Fi can improve location accuracy. This is because Wi-Fi assists in more precise geolocation services, which the app uses to automatically name your recordings based on your current location. See the Pic 2 Below
These pop-ups are essentially informational alerts triggered by features you may have previously enabled. They typically appear only when you open the Voice Memos app or attempt to edit or save a memo. Importantly, these alerts do not appear during active recording, so your recording session won't be interrupted by them. See the Pic 3 Below
Pic 1: Save on iCloud Enabled

Pic 2: Location Based Naming enabled:
Pic 3: Warning Alert Popup only when the App is opened.

Disable Save On iCloud and Location Based Naming then these popups will not appear.