[JRTJH]

If your toilet is a Thetford, in that era Thetford toilets, the water connection flange is NOTORIOUS for splitting and leaking. Since we're just now coming out of winter, if it is a Dometic look at the inlet valve body. If you see a "small round bulge" on the valve body, it is internally damaged from freezing and needs to be replaced. On either type, if the water connector on the trailer PEX line is damaged or is the threads on the valve inlet are damaged, you'll increase your probability of a leak.

Here's both valves and the Dometic "freeze damage indicator bulge".