PIC MCU: XC8 Not treating TMR0 as a 16 Bit Register
in the data sheet
section: 24.1
page 379,
It states that the time 0 can be either 16 bit or 8 bit.

Timer0 can operate as either an 8-bit or 16-bit timer. The mode is
selected with the MD16 bit
24.5.1 T0CON0
Name: T0CON0 
Address: 0x31A

the bit of interest is bit 4 of the T0CON0 register

Bit 4 – MD16 16-Bit Timer Operation 
when the bit is set to 1 TMR0 is a 16-bit timer 
when the bit is set to 0 TMR0 is an 8-bit timer

also:

Timer0 Output 
TMR0_out 
8-bit mode: toggles on every match between TMR0L and TMR0H   
15-bit mode: toggles every time TMR0H:TMR0L rolls over