1602 LCD-Screen not configured correctly

I tried to connect a generic 1602 LCD-Screen via the GPIO-Pins to my Raspberry Pi 4 but it doesn't work quite right. On the LCD-Screen it looks like this:

and sometimes like this:

The Web-GUI shows how it should look:

The LCD-Screen is from an Elegoo Uno "Arduino"-Kit but I cannot identify if it is an HD44780 Chipset or something else. The internet says it most likely is one but I cannot find any concrete evidence on the PCB or the internet. The LEDs and buttons work completely normal and without any issues.

In the configuration.txt I changed only the USE_HD44780_16x2_LCD = True so it looks like this:

Code:

# --- next display definitions are mutually exclusive = you can have only one
#
# Set True to use a 16x2 direct connected/wired HD44780 LCD, configure GPIO pins below
USE_HD44780_16x2_LCD = True
# If you use an I2C-HD44780, above option should be false !!!
# Set True or 16x2 (=True) or 20x4 to use a 16x2 or 20x4 I2C connected HD44780 LCD
USE_I2C_LCD = False
#
# Set True to use an OLED display, configure GPIO pins below
USE_OLED = False
#
# Set True to use LCD of Pimoroni PirateAudio hat. Configure GPIO pins below
USE_PIMORONI_LCD = False
#
# Set True to use a 7-segment display via I2C
# Two versions: original sparkfun display and cheap HT16K33 based ebay version
USE_I2C_7SEGMENTDISPLAY = False
USE_i2c_7SEGMENTDISPLAY_HT16K33 = False
#
# --- above display definitions are mutually exclusive = you can have only one

I checked now 10 times if I connected all the GPIO-Pins correctly and I cannot see anything wrong with it. The GPIO-Layout of the Raspberry Pi 4 and 3 should be the same right?

Does anybody know how to solve this issue?

I would recommend also to use the I2C LED, the backpack versión, so much easy. But since is not the case, it could be a bad wire, double check your Jumper wires are ok, replace them or check continuity. Also remember to check the right adress for the screen in the configuration, but is working, so maybe it's ok. I would go for wiring. That's all i can think about. Good luck!!!