Check the mask and see whether it has a pin on the strap keeper that is metal or plastic. If it's metal (stainless steel) it should be good to go. If it's plastic, it could break at an unexpected time.
Not really. It depends on the material surrounding the pin as well as the design.
For reference I use the Beuchat Maxlux S, here in the Middle East, where daily temperatures easily reach 120F in the summer, and the high UV deteriorates some plastics very quickly.
My teaching mask, spend a lot of time in direct sunlight in or by the pool. After 4 years of fairly high use the only deterioration is the the discolouration of the white skirt caused by copious amounts of sunscreen
The mask strap and retaining latches show no sign of deterioration, my second mask, newer but more dives on it, is also as good as the day it was purchased (no discolouration since its not exposed to as much sunscreen)
Modern thermoplastics are incredibly resilient and shouldn't be quickly dismissed