Updating individual apps through the Play Store is incredibly convenient, but that same system is often frustratingly unreliable, falsely claiming your apps or Android version are up-to-date even when they're not.
Play Store has a bad habit of not showing when an app update is available. You’ll often see all your apps are up-to-date, but when you navigate to the individual app’s page on the Play Store, suddenly there’s an update waiting.
Despite what your phone says, your software might not be running the most current version. That’s because both the Play Store and system updates have an annoying habit of displaying out-of-date messaging
Old information might be cached, causing both the Play Store and system updates to display inaccurate information.
first try is to head to the store page for each individual app and check to see if an update is available
If you suspect there’s a system update available and your phone says "Your system is up to date," tap the "Check for update" button again. If there is still no update, then come back in 24 hours.
Finally, the last resort is to restart your device. This could clear out caches and glitches and refresh your device’s connection to Google’s servers.
Sidenote:
ICYMI
Obtainium app
"Obtainium allows you to install and update Open-Source Apps directly from their releases pages, and receive notifications when new releases are made available."
https://counter.social/@ecksmc/112636712610020124
A handy way to keep your APKs updated, OpenSource apps, that might not be on play store or FDroid or any other app store
Even if they are on an app store i still prefer Obtainium
you'll need AppVerifier installed works side by side with Obtainium