The thermostat failed once and I replaced it myself for $100 or something like that. There's nothing particularly complicated about a hot water tank, any handyman with some moderate skills can fix or repair any issues themselves for waaaaaaaay less than the monthly rental cost with any associated "maintenance" plan.
In related news, it's probably end of life and needs to be replaced again. I'll do the exact same thing again, although I don't think I'll find one for $500 now, but no way in hell I'd every pay monthly for a water heater. I'm up literally tens of thousands of dollars at this point owning vs renting.
Electric water heaters are pretty simple things, that haven't got any new technology... EVER. A 2021 water heater might have a bit more insulation than a 1980 model, but that is the only difference.
The only thing that goes wrong is the elements and the anode... all easily replaceable. These parts cost about $20-25 each and are replaced by removing 4 bolts.
If you replace the elements and anode you might as well replace the blow off valve... another $25.
Now you, effectively, have a new water heater for $100
If you have city water a hot water tank SHOULD last forever. If you're on well water with a REAL HIGH iron content, like me, a hot water tank lasts about 4, maybe 5 yrs (I have a spare that I paid $20 for). The heater still works after 5 yrs, but the water smells like a wet dog.
Renting a hot water heater is financially stupid.
How we got "rentals" was we used to get a Flat Rate water heater, where you paid a monthly fee for the water heater AND the energy it used. The water heater was wired in BEFORE your electric meter, and the tank had a switch that would turn it off at peak hydro usage times. When I bought a house with one of these heaters in 1989, the monthly fee was $5.50. Mississauga Hydro cancelled that program in the '90's. I replaced the water heater... and found out the heater was NOT wired in before the meter like it was supposed to be, it WAS metered, so I got to sue Mississauga Hydro for 7 yr of payment... but I kept the electrical box on the fuse panel that WAS wired in before the meter... that I wired a grow op to... a win for me.
When I contacted Mississauga Hydro to tell them my flat rate water heater was metered, the nice lady on the phone tells me there is a BUNCH of flat rate water heaters wired like that, like ripping off their customers is a normal thing. I hate Mississauga Hydro!
Today a rental water heater is just a cash cow for whoever is renting it.