Lipo Battery monitoring Question

I have a 3.7V Lipo Battery connected to my FireBeetle 2 ESP32 C6.  I am using the code sample provided in DfRobot tutorial:

https://wiki.dfrobot.com/SKU_DFR1075_FireBeetle_2_Board_ESP32_C6_Basic_Tutorial

Battery Details:

Brand:PKCELL

MPN:LP785060

Li-Ion

Voltage: 3.7 V

After reading the 12 bit analog value from the analog pin of the battery they use the following calculation:

Serial.print("BAT millivolts value = ");  

Serial.print(analogVolts * 2.1218 + 1000);  Serial.println("mV");

The mV output value is reporting numbers like:

BAT millivolts value = 5466.39mV

My Question: Is this calculation correct for all Lipo batteries?  A measurement of 5.5V for a 3.7V battery seems quite high.