It’s possible for a failed tensioner to loosen the belt. The proper recommended procedure is that the tensioners always be replaced with the timing belt; no exceptions.
It’s hard to say about any warning noises. Often any growling or whining may be covered up by other engine noises and it is possible for a tensioner to fail quickly.
JMHO, but I fault whoever replaced the belt without doing the tensioners at the same time. Normally, the water pump is also replaced at this time.