M2 Pro running Sonoma 14.8.5 experiences random Wi-Fi connection issues

Your Linux laptop working normally on the same Wi-Fi is useful evidence, but it does not completely rule out the router/access point.

The quickest way to determine where the problem occurs is to ping your router itself.

First find the gateway:

route -n get default | grep gateway

Then continuously ping that address:

ping <gateway>

In another Terminal, run:

ping 193.99.144.80

Wait for the next failure.

If both pings stop responding, the failure is occurring at or before the Mac's connection to the local network.

That points us toward the Mac's Wi-Fi connection, the Wi-Fi environment, or an interaction between the Mac and the access point.

If the gateway ping continues at normal latency while the Internet ping becomes slow or stops, the Mac is still communicating normally with the router, so the problem is occurring further along the network path.

Your current ping output establishes that there is substantial packet delay and packet loss during the affected periods, but the Internet ping alone cannot tell us where that is happening.

I'd also test the Mac on a phone hotspot or another Wi-Fi network. If the problem occurs there too, that provides useful evidence that the problem isn't specific to your current Wi-Fi network.

If it only occurs on your current network, the Mac/router interaction becomes worth investigating.

Apple recommends using Wireless Diagnostics for Wi-Fi problems. Hold Option while clicking the Wi-Fi icon and choose Open Wireless Diagnostics.

Apple says this produces diagnostic information and a compressed diagnostic file that can be useful for troubleshooting.

Apple — Use Wireless Diagnostics on your Mac

You can also Option-click the Wi-Fi icon to see the current channel, frequency, protocol, signal information, IP address and router address.

Apple — Wi‑Fi settings on Mac

If you use a VPN or network-filtering/security application, temporarily disable it and repeat the test.

Apple specifically lists VPN and other security software as things to check when diagnosing Mac Internet connectivity problems. (Apple Support)

Finally, you're running Sonoma 14.8.5. Apple currently lists Sonoma 14.8.9 as the latest Sonoma release, so I'd update before doing extensive troubleshooting. (Apple Support)

The single most useful next step is therefore to run the gateway ping and Internet ping simultaneously and capture what happens when the Mac enters its several-minute hanging state. That will tell us much more than the heise.de ping alone.

On the computer, forget that particular WiFi network. Then re-add that WiFi network. Sometimes this can fix issues. I've had to do this at work for one particular SSID whereas other SSID from the same access point have no issues.