From what I gathered, the deep-packet inspection appliances they're deploying in Myanmar aren't working off terribly advanced rulesets. They only seem to be blocking obvious VPN connections since VPN protocols like WireGuard, IKEv2, OpenVPN, etc. make no effort to obfuscate themselves as being a VPN connection.
There aren't as many data points in Myanmar as one would like, but this Psiphon test from OONI seems to validate that even basic obfuscation is working in Myanmar.
Random phone checks for VPNs are definitely another level though, yikes.