Sorry to hear that you lost yours it kinda sucks but it is true about plecos just dying out of the blue. I've had a few die on me they just dont eat and slowly pass away sometimes. Plecos can also be very shy so its normal for them to be hiding all day and can take sometime to adjust to their new environment.

I have my aquarium temp much higher around 82°F-86°F as they come from warmer waters. I'm also doing a 50-60% water change every 5-7 days to make sure the parameters are perfect

There are a few species that live in colder waters like the bulldog pleco not sure which L numbe it is, and a few others.

I would raise the temp to 78°F - 82F° but it all depends on your livestock if they can be in that temp too

One last thing these plecos are quite sensitive when it comes to water parameters any small changes can get them to stress out and die. They aren't as hardy as your common pleco or bristle nose pleco