MQTT + ESP32 Wifi causes memory leakage

[kgezer]

Dear All,
When I connect Wifi and connect a broker with PubSubClient MQTT library, program works properly. I check periodically (2 sec) min heap memory level using ESP.getMinFreeHeap() function. I experienced that heap memory drops down from 250K to 212 K in 12 hours. I can see every 2 sec some times until 1K drop. At the end ESP restarts when heap reaches under 212K. What should be the issue?

Using VScode PlatformIO
platfromio.ini:
[env:esp32dev]
platform = https://github.com/platformio/platform-espressif32.git
board = esp32dev
framework = arduino
monitor_speed = 115200
lib_deps =
knolleary/PubSubClient@^2.8