2013 Gen 3 Prius – Hose keeps popping off immediately at startup (POP/smoke)

Hi everyone,
I have a 2013 Prius Gen 3 (2ZR-FXE), ~297,000 km.
I have a strange problem that started after an engine tune-up. The old PCV valve was removed, cleaned with carb/injector cleaner and reinstalled. Before this service, I had driven about 80,000 km without this problem.
Now, occasionally when I:
Press brake → press POWER → POP/pressure sound → smoke/vapour appears around the intake/throttle-body area → a hose pops off.
It happens right at startup, sometimes before the engine has properly started.
The hoses that have come off at different times are:
PCV hose
small EVAP/purge-related hose
recently, the same small hose repeatedly
After reconnecting the hose, the car runs completely normally.
There is no misfire, no Check Engine Light, EV mode works normally, A/C works normally and fuel economy is good.
Scan data shows LTFT around +11–13%, with no current DTCs.
I also noticed a slightly oily/slippery film around the throttle-body/hose area, but I'm not sure if it is oil or coolant.
My main questions:
What could cause a hose to pop off immediately when pressing POWER, before normal engine operation?
Could a PCV valve that was cleaned and reused cause this?
Could the EVAP purge VSV cause pressure to build up?
Could this simply be a bad/loose hose connection or missing clamp?
What should I test first?
I have attached photos of the hose and connection.
Any advice from experienced Gen 3 owners would be greatly appreciated. Thank you!